COOSA BOARD vs PLYWOOD Which One is BEST? Lets TEST Them Both to Failure!

Coosa Board Is Great! So is Marine Plywood! I Have built boats with both of these materials, and they both have Pros and Cons for sure! Let's Test them both to failure and see which one is best for Your next project. So, sit back and enjoy as I Break some stuff in the name of Science! You can also find lots of DIY fiberglass, gelcoat, boatbuilding and fishing related content here on our channel, so feel free to check it out.
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[@FishBumpTV]

We have made Patreon ( www.patreon.com/FishBumpTv ) available for members who are interested in consultations on their projects. Thank you for your support!

[@bryankelley6687]

There is another advantage to Coosa not many know about, that’s insulation properties, you can build a day box out of it, and have no need for foam. If you need an overnight/ multi day box, double the 3/4 Coosa, or use a poly foam with the Coosa. Very strong, and holds exceptionally. Good channel, thank you

[@FishBumpTV]

I agree, that is a good point! That aft port and starboard compartments in our custom 29 are built out of 3/4 Coosa and they hold ice very well. I appreciate you watching and commenting!

[@leerobinson7086]

There is nothing wrong with Fir plywood for boat building. There are boats around here that are 60 years old and still running strong. The main thing is to keep moisture out of the plywood. Enjoying the videos!

[@KillaCowboy]

Lol I don't think people realize that's where boats were made of for most of human history, to say wood doesn't belong in a boat is wild

[@FishBumpTV]

Haha, I know right!

[@FishBumpTV]

Sounds interesting! Thanks for the comment

[@FishBumpTV]

Thanks for your thoughts!

[@FishBumpTV]

I agree, thanks for your thoughts!

[@jasonwember9927]

How about testing them with glass applied.

[@FishBumpTV]

I think we will. I appreciate the suggestion!

[@dadzilla007]

You just sold me on Coosa, a boat needs flex, the flex isn't a bug, it's a feature.

[@paulradford4100]

Maybe use a weighted pendulum for impact test.. Thing is though, he's giving up his time for us on yt and making such testing devices may be too time consuming taking into account, he has a family and a business to run. U did find humour in those caveman style testa though.. lol

[@FishBumpTV]

Glad you enjoyed the video! I used Coosa in the 26 pound density in our custom 29, and am very happy so far. Thanks for watching!

[@debrisbox]

Might have been fun to load the ply with bricks to failure. Good time Captain!!

[@FishBumpTV]

Yes, maybe on the next test we do! Thanks for watching

[@ronaldrhatigan7652]

I built my 14' garvey with half inch marine fir plywood almost 20 years ago. I covered the bottom and chine area with 6 oz. glass cloth. Other than a few minor repairs it's held up pretty well on the Willamette River.

[@FishBumpTV]

Very nice, thanks for your comment!

[@captainmother1268]

We've tried both plywood and coosa. Coosa board is simply not as strong as plywood - where you need strength. Coosa can be good for a little box or hatch, but we never use it on a hull or stringer. Sure coosa is lighter per sheet of same thickness of plywood, but to get the same compression and impact strength you'll probably need a thicker coosa or multiple layers. The end result is the whole coosa assembly can be heavier than plywood to get the same compression and tension strength. Your impact test on coosa showed that the coosa clearly failed after the fist impat as well - it was compromised after impact. That whole argument about coosa "doesn't rot" is true, but on the other hand a plywood / timber boat that is glassed over correctly won't rot either. If the plywood core in your boat is getting wet you've got a bigger problem. Here in the Pacific Northwest we've got lots of wood / plywood boats in the water over 100 years and they are doing just fine - as long as they are maintained they will outlive all of us. And most of them have no fiberglass anywhere - they are built to keep the structural wood dry from day one. Thanks for the video, interesting test!! I would vote that you do a test again with both materials glassed over to simulate a real situation.

[@FishBumpTV]

Thanks for your thoughts! I think both materials have their pros and cons. I have used both extensively, and think that Coosa is the most like plywood in its workability out of all the cores I have worked with. My father built boats out of marine plywood and cypress frames that are over 50 years old and they are still in service, so there is a case to be made there for sure! Thanks for watching!

[@francoisduval8387]

You already published, great ! Thanks you for the production and the edicationnal porpose of your videos !

[@FishBumpTV]

Glad you like them!

[@beausworkshop3157]

Thanks for the video. This is the exact type of information I’m looking for.

[@FishBumpTV]

Glad it was helpful! Thanks for watching!

[@markturner9459]

Another great video! Thanks!

[@FishBumpTV]

Glad you enjoyed it! Thanks for watching

[@danjeffrey1531]

Hi, Capt Joe! Thanks so much for sharing what you know -- and doing it so well. I have been trying a few little projects with fiberglass for a couple of years and watching other videos as I went. But I have learned a ton from your videos! Please keep making this great content!

[@FishBumpTV]

Glad to help! I truly appreciate your encouragement and support of the channel. Best of luck with your projects!

[@dyonkers1]

FANTASTIC yall are awesome for making this. your love for the industry is evident !ytyty for making this

[@FishBumpTV]

Thank you so much!

[@csrboltfan2643]

Just stumbled across your channel a few days ago and I LOVE IT !! Subscribed !!

[@FishBumpTV]

Awesome! Welcome aboard!

[@danielbehan8069]

Love your content. I found your videos looking for ways to repair my Carolina Skiff and glad I did! Keep up the great work! Recommending you to all my buddies here in Eastern NC

[@FishBumpTV]

Thanks, glad to help!

[@user-fk6cx6xw1u]

Fish bump family y'all keeping coming really appreciate your time soaking this up like a sponge moving forward! Looking forward seeing one of the family built boats your father had a hand in building old school fir plywood and glassing maybe a field trip for all the viewers you tube Thanks again for sharing your family legacy!

[@FishBumpTV]

That's awesome, more to come! Hope to tour one of our older 37s very soon. Thanks so much for watching!

[@danballou2202]

You guys do the very best videos on these topics!

[@FishBumpTV]

Wow, thank you!

[@gsftom]

Appreciate yr video bc u spoke abt the difference in cost.

[@FishBumpTV]

Thanks, glad you are enjoying the videos!

[@Esteban-cx1jm]

I’m goin to repair my boat floor following your instruction and videos,thank you for your KZbin Chanel

[@FishBumpTV]

Glad to help, and best of luck with your project!

[@charlesclark7225]

Once again ! Absolutely great informative videos! Anyone into boating and wanting to learn repair- building process - products Pros and cons from such an experienced professional! This is the place! Years of experience packed into short videos !

[@FishBumpTV]

Awesome, thank you! I really appreciate the comment!

[@makewhatyoulike119]

Good info, thanks. I especially appreciate the list of advantages/disadvantages.

[@FishBumpTV]

Thanks, glad to help!

[@andreasmeerkamp8627]

Coosa is much more flexing as we have seen in the first test. For the impact test, it needs much more ground clearance. Very well made video!

[@FishBumpTV]

Glad you enjoyed it, I think we will do a round 2 with more fiberglass and more clearance, so stay tuned!

[@MrDangadave]

Practicality and your experience. I work in the boat industry and are very informative to me, which I can take to our clients. Thank you.

[@FishBumpTV]

You are very welcome, glad to help!

[@nathankindig3013]

Thank you, first of all, for your time. Enjoyed my 3rd video from y’all. I might need to go back to the first video. Mahalo from the land down under

[@FishBumpTV]

Thanks for watching all the way from Australia 🇦🇺 Glad you are enjoying the videos!

[@SwampBoysGarage]

Awesome content. We are rebuilding a jet ski on KZbin and noticed a big hole in the bottom. Learning a lot from your channel to get it fixed.

[@FishBumpTV]

Thanks, glad the videos help! Best of luck with your project

[@keithsanville2361]

Cool Test Thanks!

[@FishBumpTV]

Glad you liked it! Appreciate you watching

[@gfunkHP]

would love to see a diy coosa project write up-- paddle-board, pram/dinghy, teardrop trailer. just an idea. always daydreaming on new toys! Thanks for the hard work :)

[@FishBumpTV]

Thanks for the idea! I appreciate you watching!

[@tigerbait3182]

Great video's Capt. Just came across your channel and it was a blast from the past. Pretty sure we fished together way back in the day in your pirogues and at my house in OB. Solid content!

[@FishBumpTV]

Very cool, give me a call sometimes, we will have to catch up! Thanks for watching and commenting

[@Phoevos]

Another fantastic video. It would be very insightful if you could provide more information of the type of plywood (brand/type) and type of coosa (bluewater 32? 26?). Again thank you very much for all your content and the time spent to show us how its done. Greetings from Australia.

[@FishBumpTV]

Thanks, I appreciate the suggestion! The plywood was marine Fir 3/4 inch which I think would be 19mm and the Coosa was Bluewater 26. Hope this helps and I appreciate you watching from Australia 🇦🇺

[@xxxnonamexxx5615]

I use plywood around here but I can see the Coosa has clear advantages. I have a 1951 Cris Craft that has plywood in it and it's all original to this day. I just recently replaced the top of the bow but everything else is all original including the 25 horse johnson. Btw your videos are never too long. Fun stuff...

[@FishBumpTV]

I agree, both materials have there place. If plywood is fiberglassed the right way, it can last a very long time! Glad you are enjoying the videos and I appreciate you watching and commenting

[@robertmstarr9028]

Interesting test results. I've been looking at various materials to use in "reimaging" a small sailboat to teach my grandsons to sail. I've watched quite a few videos about repairing old boats, and one of the most frequently needed repairs seems to be wood rot, mostly in deck cores or around fasteners. The most beautiful boat I've ever been aboard was a fiberglass Bristol Channel Cutter with wooden bulwarks. I watched a video of an owner rebuilding his bulwarks some years ago. The sailboat I'm looking at is much smaller, and I'm older and less agile than I once was, so I've planned to add bulwarks and lifelines. I've worked with wood since I was a small boy. My dad died when I was four, and my mother remarried when I was seven. My stepfather owned a tire shop, but he had a woodworking shop for a hobby, and I learned a good bit from him. I've also worked with fiberglass in making modifications to the Formula Fords I once raced. But materials have changed, and I have a lot to learn. I've been looking at synthetics like coosa and divinycell as replacements in different applications. But I still love the feel, the smell and the beauty of a lovely piece of wood. Thank you for your videos.

[@FishBumpTV]

Glad you enjoyed the video! There are certainly pros and cons to both materials for sure. Sounds like you know what your goals are, and either material could do the job. Coosa is great for weight savings and durability, but wood is Much more pleasant to work with! If wood is encapsulated properly in modern resins, the life and durability really improves. We just released a video about epoxy over plywood. I think it might help you decide what is best for you. Hope this helps, and best of luck with your project!

[@sethbrown8912]

This is the first time that I am watching your channel. Based on this experiment alone, you get a "like" and a "subscribe". This is similar to a project that my sone did in middle school. This is clear, understable, real-world science! I am going to look for your other experiment videos. I think it is great for the uninitiated public to see how and what boats are made of.

[@FishBumpTV]

Welcome to the channel and thanks for watching!

[@stephengarcille4844]

Great content! Inspiring. I keep my boat at Homeport. I will swing by sometime and introduce myself. I enjoy and appreciate your content.

[@FishBumpTV]

Awesome, give me a call!

[@MrRushCreek]

On my tiny boat build, we used marine plywood for the upper decks and Coosa on the floors. All heavily epoxied and covered with vinyl.

[@FishBumpTV]

Sounds like a great project! Thanks for watching and commenting!

[@ontimespiva]

It’d be interesting to see the strength difference after resin and then fiberglass is applied!

[@FishBumpTV]

Thanks for the suggestion and for watching!

[@BrunoMiglietta]

Thank you great video

[@FishBumpTV]

Glad you enjoyed it, and thanks for watching!

[@motorcityboatwerks]

Great video and a great discussion. 😁👍 your videos are always informative 😁 I use coosa board in my construction and it’s proven to be the superior option.

[@FishBumpTV]

Thanks so much! Yes, I agree the Coosa is great product. I appreciate the comment

[@bigdaadio.K2WW]

I would like to see the difference plywood to coosa on edge and glassed, as some else motioned. Very informative, Thanks!

[@FishBumpTV]

Great suggestion! Thanks

[@Grudzien34]

Thanks for taking the time to do this, if possible please do a soak test with the coosa and 2 part expandable 2lbs foam and 4 lbs, Im asking this cuz every manufacturer claims that the foam is waterproof but you can find alot of videos on KZbin with boats that have water logged foam.

[@FishBumpTV]

Thanks for the suggestion! Yes, I have seen a good bit of water soaked foam also. That's why I went with a series of watertight compartments when we built our custom 29 ft charter boat. You might enjoy seeing that in some of our boatbuilding series videos.

[@1dandandy1]

Thank You. Please keep making videos about coosa.

[@FishBumpTV]

You got it! Thanks for the suggestion

[@lou_chicago]

I am now a fan of Coosa!

[@FishBumpTV]

Yes, it is good stuff!

[@user-fk6cx6xw1u]

Fish bump family WOW very impressive the plywood really surprised ! I'm sure when glassed would make a huge difference as well . wasn't sure when lamination of transoms do you put CSM between the layers would love to see how well one of the boats your family built how well it's longevity after years of service when properly sealing plywood Thanks for another great video !

[@FishBumpTV]

Thanks 👍 I think we will be doing some more testing with plywood and Coosa, with fiberglass added. Stay tuned!

[@2in2008]

I discovered your channel a couple weeks ago and echo all the good things you've already heard! I've been a fairly avid student of the University of KZbin, and your DIY tutorials are easily among the very best I've seen! I have a selfish request: I'm getting ready to do a repair on a rotten section of deck core on a 36 ft sailboat. Although there are a lot of videos out there on repairing soft decks, they vary widely and they don't take the sort of methodical approach that you guys do. Any chance you could do a master class for us on that? I'd really like to do this repair one time the right way! Thanks! (By the way, if you've already done this and I just missed it, please just point me in the right direction.)

[@FishBumpTV]

Thanks so much, and welcome to the channel! I will try to do a video or at least touch on the subject of soft core and deck rot for you guys. Glad the videos are helpful and thanks for watching!

[@FishinFool70]

I have a 24 foot Triton bay boat that is bult with coosa board.20 years old and still solid as a rock.

[@FishBumpTV]

Yes, it is good stuff! Thanks for watching

[@traumagas123]

Maybe a Live feed with questions and answers too would be great

[@FishBumpTV]

Thanks for the suggestion!

[@billnelson31]

Great video and testing. You If you do furthur testing using fiberglass on both sides of the coosa and both sides of the plywood you will find an exponential increase in strength for both composite systems, almost to the point where the strength of the core becomes irrelevant. The principle is the same a steel I Beam, where the strenth is dramatically increased as the beam depth is increased and the ‘core’ (beam web) is minimal compared to the top and bottom beam flanges. I am a retired structural engineer and have completely rebuilding a 26’ fiberglass landing craft including replacement of longitudinal stringers and decks. When we bought the hull, the previous owner had stripped it down to bare hull, including removal of the floor deck and stringers. The original stringers we glass over wood beams We replaced the stringers by forming a hollow box beam using 1/4” okume plywood because we could easily match the contours of the bottom and deck. We glassed over the hollow beams with two layers of fiberglass roving, using epoxy resin. We then sealed 3/4’ doug fir plywood with epoxy and bonded it to the tops of stringers and to sides of the hull with thickened epoxy and applied heavy fg roving with epoxy resin over the top. We have been using the vessel for commercial shrimping in Prince William Sound, Alaska for about 8 years now. To re T

[@FishBumpTV]

Yes, I agree glassing it will make it Much stronger! We plan on doing more testing with fiberglass on both sides. Sounds like you guys built an awesome work boat for shrimping! I grew up around the shrimp industry here in the gulf of Mexico as a young man and really enjoyed it. I have also been to Alaska several times, and absolutely enjoyed every minute! Thanks for watching and commenting!

[@pabloortiz1942]

Hi Joe, I am also a licensed boat operator (USCG 100GT) and third generation boat builder, (from concept) I’m diggin’ your videos and the step by step details of your content, Your experience and your articulation make these videos easy to watch and very beneficial for the millions of DIY’ers that are tuning in … Just wanting to give respect where respect is due … Good going, keep up the great work !!.. Also, might add that Coosa offers density options as well, in which case could change test results when testing in comparisons … and it’s better to screw through it than to it . Cheers !!..

[@FishBumpTV]

Wow, thanks for watching and I appreciate the comment!

[@cody2097]

The only thing thats keeping me from making the switch is "fastener holding". Like it looks like screws would easily pull through/strip etc. What about bolting up an outboard; would the coosa just compress and crack the fiberglass? If youre looking for experiment suggestions, put some screws into them and see what it takes to pull them out etc. Thanks for the video!

[@pierocicconi9706]

Very interesting

[@FishBumpTV]

Glad you think so! Thanks for watching

[@4850937]

Good. Future videos: 1. How did you get the 2900 hull design? It would be entertaining to learn your hull plug mold process. 2. Water damage management: Is it possible to fully seal? How do you remove water from the places it isn't supposed to be? Houses don't have long term sealed chambers. 3. Aluminum vs polyethylene fuel tanks

[@FishBumpTV]

All good suggestions, thank you!

[@user-yv2tz7gj2o]

Hi Capt - am enjoying your vids here in Australia. Would love to hear your take on putting gel coat/flow coat over epoxy.

[@FishBumpTV]

Thanks for watching from 🇦🇺! I have had some issues in the past with gelcoat/ flowcoat over epoxy, but I think we may do some testing with that soon, as it is a common question these days. Thanks for the suggestion!

[@nicolasweber2805]

Hi Joe...It is an impressing series you have put together, showing us of your boat building adventure. And it is very educational as well - I wanted to comment earlier, but as I only found your series this morning you cost me a whole day of working on my own estate ... in stead I learned a lot about boatbuilding through 24 episodes of building a boat - and you are doing a fantastic job building that 29 foot boat, and running your channel!! One question...? Is it correct, that you molded the whole boat in fiberclass only? no sandwich construction of the hull? no PVC or wood as a strengthener? For me, or maybe others, please keep up your awesome work with building, testing, and filming!! ( I am not a native English speaker, so please forgive my bad language or spelling)

[@FishBumpTV]

Wow, thanks! Yes, the hull is solid fiberglass laminate. We used 26 pound density Coosa board for all of the stringers, transom, decks etc. Glad you are enjoying the boat building series and I appreciate you watching!

[@chrisratliff5409]

Great video! I am currently having a Dusky restored I had reached out to see if you would build me a 29 like you have but ended up going with a 256 dusky

[@FishBumpTV]

Thanks, glad you are enjoying the videos! Congrats on the new boat

[@streamin2605]

Capt. Joe, I remember a video of you doing the front deck of your 29' boat. You where screwing the coosa down to coosa. Did you predrill and counter sink before you installed screws? Reason I ask is I've worked with coosa a good bit and I've never had any luck laminating pieces together or holding things into the coosa with screws. Usually have to clamp or squish laminations together. Also I've used a strip of wood or made brackets to mount things into or on the coosa. Thanks for the videos, they provide some insight that alot of people really dont knows out there. Coosa and 1708 for example. Most just know "angel hair" CSM or "combo" roven woving

[@FishBumpTV]

Yes, we usually predrilled and countersink the top layer only, then a very small countersink in the bottom layer, if any at all. We are using the Bluewater 26 pound density, which is the heaviest grade of Coosa. We run the screws pretty close together. There are several videos in the boatbuild series that show us doing that. Hope that helps. Thanks for watching!

[@streamin2605]

@FishBumpTV Thank you for the explanation sir!! Ive worked with the 20lb density a bunch. Never tried the 26lb. It may hold screws a little better vs the 20. May pick some up and give it a shot. My buddies got an old tunnel boat we're about to redo with coosa and poly. May try the 26 in it as well

[@shanerolfe8022]

I’m loving your channel 👍💯 every one is blinded by coosa, because it supposedly doesn’t rot🤷‍♂️ however I have removed several ( 7 ) transmons from boats that are 5/7 years old and the coosa has delaminated itself😳🤬 I have asked a engineer about this, he thinks , as do I that the material as It moves the Foam in the Material break down and make little balls that work downwards and further exacerbate the problem . People will say glass boats don’t move, that is not correct at all, they are constantly bending and twisting 💯Now don’t say I don’t use it because I do, but my own boat was rebuilt with plywood 🤷‍♂️ Footnote, I don’t know who did the transom repairs to these boats, I don’t know what resin was used ect, however they all seemed to be constructed with good laminating and tabbing techniques 🤷‍♂️. 🤗😉🐊🇦🇺

[@FishBumpTV]

Thanks for watching! That's some interesting feedback on the Coosa. I think both materials can be great if installed properly, but probably lots of poorly done work out there. Hope these vids help folks choose wisely!

[@workaholic5066]

This test is simple but practical reminder that the application of newer carbon based materials has specific and significant technological advantages in todays boating world. However, pound for pound, "old school" materials derived from mother nature have been around for thousands of years and still continue to remind us all of how to balance boating needs with renewable resources such as plywood, and still maintain superior strength while doing so. For my 2 cents... I'll stick with take the plywood for stringer repair. Great topic for the channel!

[@FishBumpTV]

Thanks for your thoughts, and thanks for watching!

[@coldspring624]

The interesting thing that comes to mind is how the two materials can affect how the boat sets and performs. I would think depending on hull design one could offer an advantage over the other

[@FishBumpTV]

Yes, I agree, thanks for watching!

[@Cheers_Warren]

The only marine plywood I trust is marine BS1088 or Ovkume type plywood. It has a full 30 min WBP (water and boil proof). I have a 1/4” plywood kayak built by stitch and polyester fiberglass taped joints , varnish else where, I built at school in 1974 and it still exists in one piece!!! The real problem with plywood is while encapsulation can make a very good product the idiots that come along later and drill hole in it , once that moisture gets in it will rot any plywood sooner or later. Love that Coosa! Cheers Warren

[@FishBumpTV]

Thanks for your thoughts and suggestions. I appreciate you watching

[@davidlee5627]

During the first impact, the Coosa board flexed downward to the point it was then being supported by the what appears to be a foam underlayment for a micro second.

[@FishBumpTV]

Yes, it did. I didn't see that till after publishing the video. The Coosa still did pretty well in that test comparatively. I use both materials a lot, and they both have good qualities. Thanks for Watching and commenting!

[@jeffreyfackett8924]

Could you please do a how to video on how to fix stress cracks

[@Hookstar67]

I really love your videos - well done. Just wondering how you go about doing the structural design work for a boat? For example, for coosa board what thickness to use for what size boat and how close together the stringers are etc. Is there a book/manual or software you use or???

[@FishBumpTV]

Thanks! I literally grew up in the boat shop. My father was a professional boatbuilder, and it is what or family has always done. We have lots of experience and we research and test alot. But it's always best to overbuild than underbuild something, especially a boat. Hope this helps, thanks for watching

[@alhash5359]

I wonder if they would perform the same way after glass is applied. Standard amount of fiberglass for a finished product?? Great job!! Keep em coming !!

[@FishBumpTV]

I think we will have to try that soon. Thanks for the suggestion!

[@RussellCompton-fh3gr]

Hmmmm looks like a combination of the two,,lam. together would be great,,,,wonder the best way to connect ?

[@FishBumpTV]

Haha, sounds like an interesting experiment! We might have to try that.

[@johnpreihs9304]

Great video on the coosa board. How is the coosa's strength for screwing things to the deck such as a seat or live well things of that nature. I'm going to replace back half of my deck with 1/2 coosa sandwiched between the bottom and top layer of fiberglass. Will need to secure things with screws and wondering how secure they'll be.

[@FishBumpTV]

The 26 pound density Coosa holds screws ok, but not as good as plywood in my opinion. We try to thru bolt the hardware with machine screws , washer and lock nut when when possible. You might want to do some testing to see if it will hold good enough for your application. I hope this helps, and best of luck with your project!

[@mannylulo]

Good

[@FishBumpTV]

Thanks!

[@mancavechronicles2139]

awesome !

[@FishBumpTV]

Thank you!

[@hubertanderson7044]

Hey Joe I’m sorry to bother you but I’ve got a I believe it’s a 70 s model thunder craft boat I just bought got to do little work on it but i love your videos and it’s teaching me to do my own work on my boat but how do you go about changing the color of the boat mines a white & blue would love to change the gel coat could you tell me how or do a video on it or do you have a video about it I’m trying to get caught up on all your videos thanks a lot Hubert

[@FishBumpTV]

Glad the videos are helpful, and we appreciate you watching. Changing hull colors with gelcoat can be pretty labor intensive, especially if it is two tone. You might want to consider going with a marine grade 2 part paint system like awlgrip if you are looking to get a glossy finish on it. I will try to discuss the pros and cons of gelcoat vs paint systems soon for you guys. Hope this helps!

[@vernesecustoms]

Great video Capt! I love what y'all do!! Was that 3/4" Coosa 15# Density? When I first learned about Coosa Bluewater 26, I was told Plywood has a density of 26 pounds per cubic foot and the Bluewater 26 was equal to Plywood. I wonder what how the same test would compare if you used the Bluewater 26. We used 26# Coosa in the Transom, 20# in the Stringers and 15# in the decks, bulkheads and Console of "Wicked Wanda". I may have to duplicate your test for my own curiosity!! Great work!I love seeing your channel blow up!! I also have to say if we could source Plywood comparable to the material used in the 1969 Bertram I am restoring, I would definitely consider building with it today!!

[@FishBumpTV]

Thank you! We used the Bluewater 26 in the test and for everything in our custom 29. I am a big fan of the Coosa products, but it was interesting to see how it compared to good marine fir plywood. Thanks for watching and commenting.

[@Krieghandt]

Now with a Ti core? Oh, you said you still have to work for a living 😀. Nice videos what's interesting, is fiberglass blows carbon away in side load tests.

[@FishBumpTV]

Thanks for watching!

[@scottgorman7166]

Seems if you applied Poly over the Coosa it would be more forgiving and flexible than epoxy over the plywood or maybe even epoxy over the Coosa since epoxy is more brittle after it has set up. What are your thoughts. And your charter is Coosa how do the seams look at the transom and where the floor meets the sides (chine) Do you have a inboard or outboard motors on the gray 29'. Great video!

[@JohnChuprun]

Your channel has so many great tips, tutorials, and tests. Deserves a lot more views and wish you all the success! Does the Coosa have the same screw/nail holding power, or clamping resistance in case of a through bolt?

[@FishBumpTV]

Thank you very much! The Coosa comes in different densities, we use the Bluewater 26 which is there heaviest. It is very comparable to plywood in many ways. I may do some testing on that for you guys.

[@JohnChuprun]

@@FishBumpTV Nice! Appreciate your hard work making these videos. Maybe someday you'll feel comfortable making a Patreon page to get the income you deserve for all this time invested.

[@traumagas123]

I am from Lillian Al !! I love the Skiff Idea Be cool to sell the Kit and Have a Group of Guys build it along with you !!! I would be in and Love to have a Skiff. I currently live in Marathon Florida Keys. Great VIDEOS !! The Best Thanks again

[@FishBumpTV]

That's awesome! I really appreciate you watching, and your suggestion on the skiff build. Who knows, maybe we will do some classes at some point!

[@Resistculturaldecline]

Which density Coosa you were testing? I may have missed you mention it. Great vids

[@FishBumpTV]

It is the 3/4 inch thick bluewater 26, that is their highest density core. thanks for watching!

[@elsuperpollo2273]

I been considering using coosa to build a custom 20 foot canoe with it, but its expensive. Even marine plywood is expensive for what I want I even thought using regular wood and go crazy with fiberglass, lots of epoxy and total boat products here in Tuscaloosa county, I want to add center console to run lights, vhf mobile transceivers. Am/fm etc.

[@FishBumpTV]

Yes, everything is pricey these days. Best of luck with your project!

[@preppervol]

Hey there Joe, I have a question… If I am doing 5 knots with the outboard and I am in the Gulf Stream going with it and the current speed is 6 knots, what effect will it have on my speed???

[@mckenziekeith7434]

It would be interesting to redo the cantilever beam test, but laminate fiberglass on both sides of each piece. My thinking is that once you laminate glass over coosa it will be just as strong as glass over ply. Do a relatively heavy ply like 10-20 oz/sq yd.

[@FishBumpTV]

Thanks for the suggestion! We might try that some day.

[@DavidMorgan-vj2rf]

Like watching all your videos very helpful I have a question I am wanting to build my own 16 17 ft skiff what is a good company to look for fiberglass molds so I can build my skiff out of fiberglass.

[@FishBumpTV]

Thanks! I don't have a particular company that I could recommend. I know there are always used molds for sale on some different boat forums. Wish I had more for you on that topic.

[@MartinRodriguez-lq8ez]

I myself prefer the plywood over Coosa primarily because of the price but also I'd rather be throwing a bunch of saw dust around over a bunch of itchy Coosa fiber dust, just my 2 cents, ❤ the video tests tho!!

[@FishBumpTV]

Yes, I agree about the Coosa dust! Not pleasant stuff! A good shop vac catching the dust while cutting, and a good tyvek suit really help though. Thanks for watching and commenting

[@dsmith657]

In my engineering opinion both dynamic test samples failed on the first drop. The COOSA has a smaller fracture but most of its stuctural integrity is exhausted. Its clear that the coosa is a more flexible material than the comparative plywood. This flexibility could be considered a failure or an asset. For example a very flexible bridge would not work in that application, ie would likely not be used by us humans. On the other hand flexiblity could be a required design feature. Used as core material with GRP top and bottom then we have beam, where the top and bottom fibres become the main structure resisting bending loads. Failure in these cases is therefore likely due to shear loads at the core COOSA grp glue bond. If COOSA is superior in this respect then it might out perform grp coated plywood. Finally I'd comment that structural failure is a complex subject and there are whole books writen about it. Great channel, been messing about in boats all my life, so really appreciate your time and effort in making these videos. COOSA unfortunately seems not to be available on the UK

[@FishBumpTV]

Glad you are enjoying the videos and thanks for watching!

[@williambusby146]

Have a question for you. I've seen oriented stranded board (osb) fiberglassed and I'm wondering what is your thoughts on that ? Not everyone in the boating world can afford these high priced plywood. What csm or woven would you recommend for the osb? Could you possibly go through the procedure of that ?

[@FishBumpTV]

I will have to do some research on that. I have personally never used or seen osb used on any kind of boat work in our area. Wish I could be more help on that subject for you. Thanks for watching!

[@JeffreyDRein]

Steel rusts & rots too without regular paint and maintenance

[@FishBumpTV]

Very true

[@JasonChristman1]

How do you make 11" x 14' stringer wrapped in fiberglass when plywood or coosa only comes in 8'

[@FishBumpTV]

We always make the stringers with two layers, and stagger the joints. That way you can make a stringer as long as you need. I have a stringer and transom video here on the channel with a demo piece showing how you would do the staggered joint. I hope this helps and thanks for watching!

[@joebrenner4428]

30-40% lighter than plywood plus all the sealer and plywood soaks it up.I might glass over the Coosa too but a substantial weight difference.

[@FishBumpTV]

The Coosa has definitely got some great qualities. We used it extensively in the build of our custom 29, and I am very happy with it. Although a good marine plywood that has been fiberglassed properly still has a place. Thanks for watching and commenting!

[@frojasfl]

Flex is fine, no part of a boat will have that much pressure on a small surface area for that long (unless it is poorly designed). Ply will always hold a higher static load as you tested it, due to the layers being glued together as opposed to an extruded or molded composite sheet. I wonder how much stronger they are with resin applied... Besides, Coosa has something ply can never overcome... resistance to rotting and moisture retention.

[@FishBumpTV]

I appreciate your thoughts. Thanks for watching!

[@johnelser9256]

Using Coosa also brings up the resale value when you sell also plywood soaks up a lot of epoxy bringing up the weight of material with all the work involved in doing stringer’s or transom Coosa is only way to go

[@FishBumpTV]

Good points, I appreciate your thoughts!

[@neutralmind6047]

Great video keep them going your impact test needs to be higher than the one brick because it was bouncing on the styrofoam therefore you could put a hundred pounds on it and it would not break

[@FishBumpTV]

Yes, we will be doing round 2 of testing soon. Thanks for watching!

[@kenmoule825]

LVLs should be tested to make all of these tests three materials.

[@TheSpadre]

The biggest problem with plywood is other people's perceptions. Too many boat builders used wood in their construction but didn't take the proper measures to ensure that it would be encapsulated. I'm about to restore a 1985 Aquasport CCP 250, but I am struggling with the decision to use wood or Coosa. I would be completely comfortable using wood, but one day, I will likely want to sell the boat.

[@FishBumpTV]

I agree! Hope the videos help you make your best decision. Best of luck with your project!

[@user-qk6og1hy3u]

What advantages are there with plywood. I only use coosa anymore.

[@rogervondach1238]

Since there is a big price difference, it would be interesting to know an endresult. The plywood needs to be completely sealed, but the Coosa product does not need that. There has to be a fairly big time difference as well and time is money too. Maybe you can give us a sample!

[@FishBumpTV]

Yes, the plywood needs to be completely sealed, but we do fiberglass over the Coosa in most applications as well. I agree that any time saved working with one or the other is a value as well. I have used both materials many times and there are definitely pros and cons to each. Thanks for watching and commenting

[@iSKM183]

plywood has fibers on the outer layers. if you do a test when the outer fibers are along the board being tested, then it is strong, but if across, it will bend like Coosa and break earlier

[@FishBumpTV]

Yes, there are some variables for sure, so we will be doing more tests soon. Thanks for watching!

[@russellfaith8959]

How would have built the 29’ differently if you were to use plywood? Secondly what is your plan if murphy shows up and you now have water in the bilge?

[@FishBumpTV]

We have built quite a few fiberglass hulled boats with marine plywood superstructure that has been encapsulated heavy with fiberglass. If done correctly it can last last many decades. But you guys should use which ever product that you feel best suits your needs. Thanks for watching!

[@douglasthompson2740]

Would have been interesting to see how much more the plywood would take. It pays to bear in mind that they plywood is going to be much more variable as it depends on the plies and the quality of both them and the glue. That being said I cannot say just how good the quality control of Coosa is to predict if failure will be the same sheet to sheet.

[@FishBumpTV]

Yes, I think we will do a 2nd round of tests, with fiberglass added next time. It should be interesting!

[@panagiotisgiannoulis3747]

Good morning from Greece, is the thermolite panel the same as Coosa? In Europe we have thermolite

[@FishBumpTV]

Very nice to have you watching from 🇬🇷! From what I understand Coosa board and thermolite are very similar materials. I will try to do some research on that for you guys.

[@mannylulo]

Greetings Joe. I am in the process of laminating the floor of my boat. I am using bondo resin, do you think it can be used? thank you

[@FishBumpTV]

My understanding is that bondo brand resin will have wax added to it, and is not really considered laminating resin. We use a high quality iso polyester laminating resin made by polynt on most of our projects. Resins are like many things, there is going to be good, better, and best. I recommend using the best materials you can get if possible. Hope this helps, and good luck with your project!

[@mannylulo]

@@FishBumpTV thank my friend

[@mckenziekeith7434]

Maybe I missed it but which density of coosa did you use? And what kind of marine ply?

[@FishBumpTV]

The Coosa is the Bluewater 26 pound density, and the ply was 3/4 marine fir. Thanks for watching

[@mikejustice1196]

Where is the number one video on the 29 ‘boat you built please

[@FishBumpTV]

kzbin.info/www/bejne/h2a8o5toh61leas How to Build a Boat- Ep# 1- The Fiberglass boat building process Thanks for watching!

[@hermanwandall4069]

Hi Joe could you give us an idea of how much fiberglass and resin you would use on about 350sf of plywood? I’m doing a project and it seem a little difficult to figure out exactly what I need. Thanks in advance! Herman

[@FishBumpTV]

It would depend on how many layers of glass you would be putting on. Plywood needs several layers of fiberglass, plus a couple coats of gelcoat in most cases. 1708 takes around 2 to 3 ounces of resin per square foot to wet out. Your resin supplier should also be able to help you with estimates. Hope this helps, thanks for watching!

[@hermanwandall4069]

@@FishBumpTV thanks so much! You’re doing a great job. I’m just a little apprehensive about starting as I want it to turn out with a professional finish. I will continue to watch and learn.

[@user-dv7hb2sc9m]

How many layers of fiberglass would you say is the least amount you'd use inside the hull of your boat? I watched how you did multiple layers & tied the bottom to the Sides & then the Sides to the top edge in a manner that made it almost like one complete piece. Back to my question, did you roughly use 3 layers or more & I can see using additional layers between surfaces. I'm only asking a ballpark number ; like 4-5 layers in the bottom? Just a basic general number if I can ask? Good video, I've been on a lot of these now. peace

[@FishBumpTV]

Usually the larger the boat, the more layers of glass you would use. On my 29 we did 2 layers of 1 Oz csm for a skin coat, then 6 alternating layers of 1708 and 1808, 3 of each. Then the stringers were glassed in with 3 layers of 1708, and one more 1708 tying all the spaces between the stringers together. So most of the bottom is 10 to 12 layers thick. Hull sides are 2 layers of 1 Oz csm then 6 layers alternating of 1708 and 1808. That makes for a very solid boat, and may be a little overkill, but I don't want to be worried about if she is going to hold together when it's rough. I hope this helps and thanks for watching!

[@user-dv7hb2sc9m]

Thank you for all of that...... while I'm lost you've talked about various "grades" of glass & that will prompt me to research deeper using what you did as my baseline. Yup, I'm not afraid of the prep & hard work as much as I'm afraid of F#@Kin' it Up & having to redo something b/c I didn't do it right the first time. Anyway I look at it, I'm learning so I TY very much!

[@Lumberjacknooj]

What is your opinion on foam core stringers?

[@FishBumpTV]

We typically use Coosa or marine plywood, but I have seen foam cored stringers work on some smaller boats. Wish I had more for you on this subject. Thanks for watching!

[@VitiProa]

If you compare verbally coosa to marine plywood, why you use a a bar of lumber, not a bar of plywood for experiment? Plywood would break earlier. In structural comparison fatique resistance is also important, so only static test is not adequate. But anyway, nice to see new materials. Thanks

[@FishBumpTV]

Please look closer. The material we used is Fir marine plywood, not lumber. We cut both pieces used in the test from the same exact larger sheet of plywood so the test would be as accurate as possible. Hope this helps clarify. Thanks for watching