Fast boat modified outboard

This is the initial test run of the modified lower unit I made.
Plenty more setup required but I’m very happy with the initial results.
Subscribe for further videos on this motor.

[@josephhalwagy6435]

Well done mate. I am truly envious of your speed in such a small tiny

[@25hpboatracerman]

Hi mate, Thanks 😊 I really appreciate your comments. The little tinny feels awesome 👏 cheers 🍻 Aussie Boat Guy 😎

[@FlyingZombiekiller]

Crazy motor mate. I love your videos😄

[@25hpboatracerman]

Hi champion thanks mate, it’s starting to really go quick 😁 cheers 🍻 Aussie Boat Guy 😎

[@TV-nr7tt]

Love your vids! Especially the prop videos. I'm also going to try make a cleaver for my boat! From the Netherlands.

[@25hpboatracerman]

That’s awesome mate, lots of work but rewarding. cheers 🍻 Aussie Boat Guy 😎

[@user-fz1eg5yc9k]

I am now subscribed...I enjoy it every time! keep it up greetings from the Netherlands

[@25hpboatracerman]

Hi mate, that’s awesome 👏 and really appreciate the support. cheers 🍻 Aussie Boat Guy 😎

[@bunndyboy]

Looking forward to the 15 super modified 😂

[@25hpboatracerman]

Hi Champion, Me too 😂 Got one sitting in bits in the Garrage, I really want to finish my seawasp boat build first, too many exciting projects. Cheers 🍻 Aussie Boat Guy 😎

[@MarkValascun]

Bro that CSR hat is a THROWBACK!😮‍💨

[@25hpboatracerman]

😂😂 Yeah, I don’t really care much for fashion 😆 I prefer the smell of burnt two stroke. cheers 🍻 Aussie Boat Guy 😎

[@bradleyfarquhar2023]

Pretty fast mate woohoo goes well cant wait to see the next video.

[@25hpboatracerman]

Hi Champion, Yeah, feels like it moving too, but sketchy from time to time 😂 cheers 🍻 Aussie Boat Guy 😎

[@drewmacmillan6954]

Love it! My 10 ft tinny with modified 8 hp , not as fast as you. It scared the the crap out of all that drove it. Cheers

[@25hpboatracerman]

Thanks Mate, Well done with your boat and 8hp 👌 it’s amazing what can be achieved with such a small motor. cheers 🍻 Aussie Boat Guy 😎

[@onemantwohands5224]

Excellent 👌 loved seeing the leg in action! I've had an idea to shorten the whole leg to get the engine down further but it's obviously a huge undertaking. A good one since your engine is already developed and could be a future endeavour! I've got facilities at home for this type of thing so let me know if you need machining done 👍. Love the content mate and have the Tohatsu 9.8 for mods that you've given us already 🎉cheers mate🤟

[@25hpboatracerman]

Hi mate, Really appreciate your comments 👌 Yeah, I thought about a short leg but the whole motor is so light I didn’t bother. Normally shorted to lower the centre of gravity but would like the tiller out of my ear 😂 cheers 🍻 Aussie Boat Guy 😎

[@DktheWelder]

That must be scary going so fast on a tiny boat! Can’t believe you made that prop!

[@25hpboatracerman]

Hi Legend 👋 Definitely fun 🤩 I made a prop because it’s something I always wanted to do, so glad to finally use it on something 😁. cheers 🍻 Aussie Boat Guy 😎

[@glennllewellyn7369]

Well done mate!

[@25hpboatracerman]

Thanks Mate 👍 I really appreciate your comments. all the best, Aussie Boat Guy 😎

[@needmoreboost6369]

Very Nice work on the surface drive! 👌and some angry looking props too! I love tohatsu motors and as far as I’m concerned they are the best! Ever thought of modifying the hull? I’ve got a few tinnies and I’m thinking about either converting a conventional v hull Quintrex that is quite slow into a stepped hull or making a combo hydroplane/ v hull by adding a bit of sheet here and there. I’ve got tig welder so smaller jobs aren’t too bad but until I get a mig the project I want to do most is splitting one in half and making a wide stepped hull cat! but that’s an altogether different level of project! and more for time and materials than I’m willing to spend(for now now anyway)

[@XSAILOR65]

That's insaine speed mate, good job! Must feel like 50 knots on that small boat!

[@25hpboatracerman]

Hi mate, yep, feels like it moving for sure 😁 cheers 🍻 Aussie Boat Guy 😎

[@robertnewland90]

Man this inspires me to mod my tohatsu 30hp it's currently hitting about 67ks Max.

[@weilfast]

Nice work!

[@25hpboatracerman]

Thanks Mate, it’s been a very fun project. cheers 🍻 Aussie Boat Guy 😎

[@benashby6162]

Looking forward to the low water pick gearcase video.

[@25hpboatracerman]

Hi mate, Thanks, I’m looking forward to it too, just need to edit 😊 cheers 🍻 Aussie Boat Guy 😎

[@ningken.barau30]

Very nice engin,very fast

[@25hpboatracerman]

Hi mate, really appreciate your comments, it’s been a lot of hours to get it where it is now. cheers 🍻 Aussie Boat Guy 😎

[@a3_Beats]

I love these vids, i want to Get a small race Boat and make the motor like How u do it, i love watching rooster tall and How the prop spins on the surface😮😮

[@25hpboatracerman]

Thanks mate, really appreciate your support 👌 Yeah, I’m the exact same, so awesome surfacing props and rusted tails 😊 cheers 🍻 Aussie Boat Guy 😎

[@reliantscimitar130]

It was just dripping water at full speed, check the cooling flow , great job👍

[@25hpboatracerman]

Hi mate, Thanks 😊 pretty sure what can be seen in the footage is not the tell tale, just the trunk outlet connected to the thermostat outlet. I did keep a consistent look at the tell tale. cheers 🍻 Aussie Boat Guy 😎

[@nicholaschriss1706]

61kph is insane for a little engine like that!

[@25hpboatracerman]

Hi Champion. Yeah, I’m pretty happy with the top speed, of course still trying for more. it took a heap of mods to get that speed but I’m sure with some more setup I might get even more. cheers 🍻 Aussie Boat Guy 😎

[@FAKE-NAME]

61km good job that's what my 90hp does on my 16' fiiberglss runabout 61-65km probably a bit more solo but I've needed passenger weight to help balance the boat

[@25hpboatracerman]

Hi Mate, yeah it goes really well, bet your fiberglass boat is more comfortable 👌 Happy New Year 🎆 cheers 🍻 Aussie Boat Guy 😎

[@kyzor-sosay6087]

Excellent,man.Add you some leading edge cup to that prop,will help with your hole shot.

[@needmoreboost6369]

Could add some to the trailing to get more top end? Fair bit of meat to work with!

[@25hpboatracerman]

Hi mate, thanks for your encouragement 👌 Not sure if you mean trailing edge? cheers 🍻 Aussie Boat Guy 😎

[@pauldavis4656]

That little unit is scooting!

[@25hpboatracerman]

Hi mate, Yeah, she screams along 😁 I’m hoping for more still though 😂 cheers 🍻 Aussie Boat Guy 😎

[@72mardy]

Thats so awesome 😁

[@25hpboatracerman]

Hi mate, Thanks 😊 loving it 👌👌 cheers 🍻 Aussie Boat Guy 😎

[@vistkri]

Thats awsome!🎉

[@25hpboatracerman]

Hi Mate, Thanks 😊 I’m having so much fun tinkering with these little motors. Cheers 🍻 Aussie Boat Guy 😎

[@peirsariou4001]

What fresh #### have I just subbed to? Insane 😂😂😂😂 rock on 🤘

[@25hpboatracerman]

Hi Mate 👍 Welcome aboard. all the best and cheers 🍻 Aussie Boat Guy 😎

[@YouTube_user3333]

Change the power head to the 18hp. 😂 I knew the 13 pitch clever was going to be better. It also has room to cup and thin the blades out. I had a similar setup. 4m tinny lightweight with a light weight 50 hp 3 cylinder, jacked up to the moon. 74km/h. Good times 🤙

[@25hpboatracerman]

Hi Mate, The 50hp setup sounds fun 🤩 Unfortunately my motor is the 6hp - 8hp - 9.8hp leg and block and the 18hp powerhead will not fit, it’s way bigger. my motor is only 169cc the 18hp is 294cc. I do have a few 18hp motors here though, may modify one in the future. cheers 🍻 Aussie Boat Guy 😎

[@johndoe1778]

Bloody oath bro loving it Cheers, now with all that motor out of the water need to start getting that hull out of there to! Couple wings maybe in the future?

[@25hpboatracerman]

😂😂 Don’t think I haven’t thought of that because I have 😁. thanks for your comments mate 👍 cheers 🍻 Aussie Boat Guy 😎

[@yelyab1]

What about extending the wetted water length with some long skinny tabs like on the big off shores. Seems it would really help stability and the boat get up to speed so fast gives the impression there is a lot left. It good to see somebody giving lessons in prop position for speed. I talked to a Yammy factor rep several years ago at Miami boat show and he said most boat builders put their props way too deep under the boat. When I went from go fast to center console I went and had after market Jack plates added. What a difference, especially in fuel economy. Without the plates I would never have been able to get the engine rpm’s up to the rated numbers.

[@25hpboatracerman]

Hi mate, Really appreciate your input and trim tabs are a good suggestion 👌👌 Yeah, jack plates can make an awesome difference. glad your enjoying boating champion. cheers 🍻 Aussie Boat Guy 😎

[@vibratingstring]

On a tiny boat like this, with a motor that can be trimmed, the addition of tabs of any significant size is nonsensical. Trim is controlled by the engine. It isn't an inboard. However, the last foot and last inch of the buttocks makes a huge difference. An aluminum boat can easily get a hook or a rocker to it and this needs to be worked with. Adding small tabs all the way across could help with that. Long skinny (as in long chord, short transverse) are very inefficient. You want tabs to be chine to chine. A small amount of rocker into the buttocks in the last 6 can be trimmed away with tabs, to get the right behavior. But it can also be done with a little epoxy bog after trials with the rocker. Also interceptors are another way to add lift at the transom.

[@bayoumike544]

Move the outboard back about 30cm from the transom will gain more speed. Currently I run a 20 foot aluminum boat in Louisiana with the outboard back about 2 feet from the transom. With a stock 200 Johnson it runs close to 60 knots at 5800 rpm. The hull is a bit heavy being built out of 3/16in aluminum with dual consoles and set up for fishing in the marshes. Great job on your project so far and want to see it continue. Going to check the low water pickup video and maby add that to my rig to raise the engine up more since I travel shallow water most of the time

[@25hpboatracerman]

Hi mate, Yeah, pods do make a good difference on some boats and have run them on a few setups in the past with great success. Unfortunately this boat is only about 8ft and running a pod would upset the balance and make it very unsafe. Your onto a winner though with the longer boats, pods (moving the outboard back) can really improve things. cheers 🍻 Aussie Boat Guy 😎

[@chiphill4856]

If you move it back,you gotta move it up too, because the water rises behind the transom underway.

[@bayoumike544]

@@chiphill4856 Mine is up about 6 inches. Bit rough on tight turns.

[@mercmanwon]

Don’t see what any setback would accomplish. Setback is mostly for moving the center of gravity back in the boat. That’s useful on a heavier boost. Here all he needs to do is lean forward or back for instant adjustment. As far as motor height goes he can’t go any higher. The only maybe to going back is to be in cleaner water but I’m not sure that’s a real problem at this speed.

[@bayoumike544]

@@mercmanwon The farther back from the transom a motor gets lets the water turbulence settle just a split second meaning the prop gets a better bite.

[@Bill-wz6tw]

Just from looking at the angle your engine is tilted it looks to be in the position to help get on plane( It is lifting the stern up ) but it wont run out its fastest in that position you need a method to trim the engine while running to get the right spot dialed in for top speed I always trimmed the engine up to get a slight porpoise for the fastest speed and then come back on it until the bow would settle down and run relatively light but not oscillating too much. This trim adjustment cannot be left or done manually ahead of time because if you try to take off from a stop with your engine trimmed for top speed it will send the bow to the moon and never plane out and it is also dangerous because of a loss of forward visibility during acceleration

[@25hpboatracerman]

Hi Mate, I agree and will be trying to make something when I get some more time. Difference props will possibly help too. cheers 🍻 Aussie Boat Guy 😎

[@kennethnoisewater1502]

Would it be less sketch with a remote throttle and steering? You could have the airboat style push pull steering stick mounted on a pivot in the bottom of the boat with some steel cable and pulleys for little weight

[@25hpboatracerman]

Hi mate, I like it 👌 I have been thinking of steering wheel, we will see 🤷‍♂️ cheers 🍻 Aussie Boat Guy 😎

[@gregpenhaligon7859]

The skeg on the gear box looks to be larger than needed, causing some drag. however when you run that high it is easy to cavitate the skeg and loose steering in a turn. Are you running higher oil /fuel ratio putting the engine under that load with the number of RPMs it is doing?

[@25hpboatracerman]

Hi mate, Yeah, the reason did the large skeg is for steering when running that high. I’m running 50 parts fuel to 1 part two stroke outboard oil, so every 5 liters of fuel I run 100ml of oil. cheers 🍻 Aussie Boat Guy 😎

[@marcomantovani5425]

interesting video, some questions: what power does the engine have? What make and model is the propeller you mounted? and where did you buy it? Thank you

[@25hpboatracerman]

Hi Mate, Thanks 😊 The motor is a highly modified 9.8hp Tohatsu two stroke (plenty of vids on the channel about that motor) The Propeller is a one off custom propeller and is not available unfortunately. cheers 🍻 Aussie Boat Guy 😎

[@tiller_gorilla7220]

Crackin.im thinking you may be able to drop the motor down a touch with chrome prop after you thin it out.just throwin it out there.

[@25hpboatracerman]

Hi mate, You are probably correct 👌 I still want feed revs though for top end speed but lowering slightly will settle the boat too. cheers 🍻 Aussie Boat Guy 😎

[@emanuelpichelli2189]

Really interessed about the homemade cleaver propeller. Any video on how to build it?

[@25hpboatracerman]

Hi mate, Yeah it a cool little propeller 👌 Unfortunately I built that before I was videoing that sort of stuff. It really was a lot of work, like 100hrs 😂 I mage the hub, the tube, the blades all separate then made a jig to hold the blades where I wanted and welded them on, then grind, grind, grind, sand, sand, balance, polish etc. cheers 🍻 Aussie Boat Guy 😎

[@marvelous877alzadward5]

Yo dude..next video please making the tunnel boat and try use this engine,by the way your working is very owesome..good job ✌🏻

[@25hpboatracerman]

Hi Mate, Unfortunately won’t be making a tunnel, as awesome as that would be. I may however get the chance soon to try that motor on an actual race boat. cheers 🍻 Aussie Boat Guy 😎

[@NinoSpinner]

Elica spettacolare, l'hai costruita tu? Quindi alzando il fuoribordo anche di poco si migliorano le prestazioni?

[@25hpboatracerman]

Ciao 👋 Sì, sollevare l'elica migliora le prestazioni, devi solo assicurarti che l'elica non subisca cavitazione o ventilazione. Ho modificato l'elica da un'altra elica che avevo. L'aggiunta di qualche piccola coppettazione all'elica di serie può consentire di farla girare più in alto. saluti 🍻 Ragazzo australiano in barca 😎

[@Outboardtech]

If you trim it down it will plane easier and feel better

[@25hpboatracerman]

Hi Mate, Yes true, I have tried that, it also goes about 5kph slower. This boat is just for some fun and tests to see how fast I can get it to go. Cheers 🍻 Aussie Boat Guy 😎

[@bcbrando7678]

Weeeeeeoooo!!! Look at that roost !!!!

[@25hpboatracerman]

Hi mate 👋 yeah, it flipping awesome, loving it. cheers 🍻 Aussie Boat Guy 😎

[@lasthryx7854]

hello well done thing is awesome!! curious on the prop specs and also if an outboard like this will perform well on a RIB!! I got a Mercury 15hp 2 stroke that I like to modify

[@25hpboatracerman]

Hi Mate, Thanks, I appreciate your encouragement 👍 The Prop is roughly a 8.5 x 15 which I made out of a bigger prop cut down. The merc 15 super (Japan built ) are awesome for modifying. The USA 15 Mercury is harder as most of them are a lost foam casting making it very hard to get to the ports as the head isn’t removable. Either way, props and engine height are the key to speed. Remember though it will be harder to get on the plane and torque steer will come into play (you will have to fight the tiller all the time if running surfacing props) Cheers 🍻 Aussie Boat Guy 😎

[@lasthryx7854]

@@25hpboatracerman hey thanks for your response!! I got the 15 super version (Japan) so that is something positive, I suppose that your video about modifying the 8HP is a great guideline to modify the 15HP. I Just need to search for a suitable prop, do you maybe have some tips or a guideline for choosing the right size prop? Thanks!!

[@25hpboatracerman]

Hi Champion, Plenty of options for the 15hp super, it’s actually the 18hp Tohatsu block with the larger 60mm bore (check out my 18hp - 15hp - 9.9hp comparison video) They are raced here in Australia so depending on how far you want to go with it, sky is the limit. Remember as soon as you start surfacing a prop it is more unpleasant to tiller with the torque steer etc and getting up on the plane becomes more difficult. Gotta sacrifice something I guess for ridiculous speeds. I will have nose cones for that motor soon if your interested Cheers 🍻 Aussie Boat Guy 😎

[@lasthryx7854]

@@25hpboatracerman Hey! Sick I'm so stoked to start the build. I'm also really interested in the nose cone for the 15hp would make things alot easier instead of fabricating it myself. I'm currently building the jackplate with a rotating handle to adjust the height, pretty much like the ones from on the fly

[@ianmoone2359]

Surface piercing props is a bit of a science to get right. You’re on the right track tho. Perhaps you could alter the ratio of the gear set in the lower unit to increase the rpms on the surface piercing prop? They do like to spin faster than a normal OB lower unit will allow at engine WOT generally. Have only run much larger setups on fast lobster boats, ie twin arnessons on 1000hp & a pair of sea fury surface drives on 2000 hp. 42 knots & 48 knots respectively.

[@25hpboatracerman]

Hi mate, Thanks for your comments, I love the big surface drive setups, haven’t played with them personally. I may be able to find one other ratio to fit that gearcase but it is a 2 to 1 and at the moment it’s running a 2.08 to 1, not sure if that would be enough of a difference to worry about though 🤷‍♂️. I still need to try another few props as I feel they are still not optimal. I also saw a section on the hull (lifting strakes) that are built very badly and would be causing drag which I will focus on next. All the best and cheers 🍻 Aussie Boat Guy 😎

[@ianmoone2359]

@@25hpboatracerman failing a change of gear ratio, about the only other option is to increase pitch. Because surface piercing props aerate the water they run in, the slip factor is quite high, so you can get away with more pitch than a standard full blade sub surface prop. This might help. “Camber and cup, especially near and at the blade tip, reduce slip. 'Slip' yields the pitch of the helical wake, which is less than the blade pitch. The blade pitch increases from leading to trailing edge on high speed props (flat blades are for ships and fishing motors). The low pressure side is highly cambered, the high pressure side should also be cambered. Slip can appear a a factor in the mechanical efficiency. For high speed craft (raceboats )mechaanical efficiency is .6 to .7, slip is about 5% at mid-chord, and a properly designed surface-piercing prop ha about zero slip at the leading edge.”

[@25hpboatracerman]

Thanks for all your input on this mate 👍. The standard submerged prop for that motor was a 8.5 pitch and the stainless cleaver I’m running is a 13 pitch, the brass chopper is a 15 pitch so already gone up in pitch a lot, I still want the revs to reach over 7k as my power is at 6200 to 7200 rpm from my tests after all the mods I have made to the powerhead - exhaust - intake etc. I am still yet try try the brass prop after adding a small cup the the trailing edge, hoping it helps. Cheers 🍻 Aussie Boat Guy 😎

[@ianmoone2359]

@@25hpboatracerman You definitely sound like you’re on the right track. Surface piercing props have that characteristic rooster tail they shoot out behind when they are operating efficiently. I noticed yours doing just that in one of your WOT runs, so you can’t be far off having it close to optimal I’m guessing. With the arnessons they run from ZF Marine gearbox, so there’s ratios increased from the engine crankshaft rpms, then through jackshafts, out through the transom - so you can bury both props on takeoff so they are fully submerged - to get enough bite to launch without the props ventilating and slipping so much. Then as you get up on plane, you lift the props until the boss is at water level and they become surface piercing. I notice you have a fixed jack plate with your OB height fixed so you don’t have that option. But Bobs Machine Shop in Florida do make electric height adjustable jackplates so that you can raise your OB height on the fly, effectively achieving what the arnesdon out drives do . The big “risk factor” with lower unit gear case water pickups, is that if you raise the gear case water pickup point slightly above water level you lose prime on your water pump and stop circulating cooling water through the head & at WOT that cooks the motor in mere seconds. So the key thing the flats boats who typically run shallow and employ Bobs Low water pickups modified gear cases and hydraulic or electric jack plates is they have a water temp guage on the dash that you watch like a hawk for any temp increase as your raining the OB on the fly. Any sign of increasing temp and you lower the jack plate height to stay in optimal temps range. Something else they do, is alter the water pump pee stream nozzle so that it shoots up into the air - and they have a rear view mirror (like a car) on the dash so you can see the pee stream visually behind you while driving and adjusting jack plate height and trim tabs etc. If you really wanted to go faster you should consider a twin hull that has a Hysucat style foil between the sponsons to lift the sponsons higher in the water to reduce wetted surface area reducing drag. The 2 fast cray boats I was on were both “vortex” style hulls, where the side sponsons are set forward far enough to catch & ride the bow wave thus harnessing that otherwise wasted energy, and lift the hull much like a foil does on a cat hull. The 42 footer had twin Iveco 500 hp diesels running through ZF gear boxes to the arnesson outdrives with their jack shafts. It was a Abrolhos Islands cray boat off the WA Midwest coast that ran 42 knots and drew only 6 inches on plane. The Abrolhos is a place with lots of very shallow reefs that originally were fished with jet boats to get in shallow to set pots in the holes in the reef where the crays lived. The surface piercing vortex hull achieved the same result. The replacement boat was still a vortex hull but 48 feet this time so 6 feet longer & it had twin 1000 hp Cat C12’s turbo diesels again through ZF Marine gear boxes, but this time through the New Zealand Sea Fury Surface drives. The transom was sloped back at ~ 45 degrees and the prop shafts went straight through the sloped transom with cutlass bearings and rudders behind. You couldn’t lift or lower the props their height was fixed to have the prop bosses at surface level on the plane. It drew 6 inches but ran 48 knots. The Abrolhos Islands were 54 nautical miles offshore from Geraldton and it was an hour and a quarter trip on the right day. The technology works well if you get it right but there’s a bit of trial and error both setting it up right but also learning how to drive it to best effect, because it’s not like most other boats.

[@danhillman4523]

LOL. Aussies love their tinnies.

[@25hpboatracerman]

Hi mate, Yeah, it’s so true 😂😂 all the best and cheers 🍻 Aussie Boat Guy 😎

[@danhillman4523]

@@25hpboatracerman Ya, nah. I think it's cool. Love those props.

[@gabbermaikel]

would be nice if you had a log system that had gps speedo and rpm with it. That way you can really look at what is going on and tell what needs to happen to maybe gain a bit.

[@25hpboatracerman]

Hi mate, You are spot on and I have a little book I write those things in as I do run the tacho and have the gps onboard. I get more strict when I’m near the end or top end of tuning and setup, even temperatures the day I’m running as that definitely makes a difference. cheers 🍻 Aussie Boat Guy 😎

[@Outboardtech]

Also the water is less distorted

[@25hpboatracerman]

Hi Mate, Not sure what you mean but if I lower the motor or trim it down the boat goes much slower. I will probably put a standard case and prop back on, drop them motor back down and trim it in a tad once I’m finished trying to see how fast I can get a modified 9.8hp to run, I’m going for 65kph hopefully. that’s faster than my 30hp on a 11ft aluminium bpat which is setup standard. Cheers 🍻 Aussie Boat Guy 😎

[@Outboardtech]

@@25hpboatracerman I like it I think it works

[@Outboardtech]

@@25hpboatracerman I think it needs to go higher with less angle

[@jonathantheunacceptable4259]

Do you troll slower at idle with one of these style of props? Main question I guess, is there more slip at low rpms?

[@25hpboatracerman]

Hi Mate, For sure, definitely more slip at low rpm, unfortunately too much. It is even worse if you run a non tubed race prop as even more air and exhaust cause cavitation and ventilation at low rpm. Cheers 🍻 Aussie Boat Guy 😎

[@jonathantheunacceptable4259]

@@25hpboatracerman thanks, I have a old prop I want to try to alter. I want to be able to troll slower, around 1mph but still get up to 30mph when I open up the old 85 evinrude lol

[@Dunkolunk]

Awesome, do you have a video of modifying the lower unit?

[@25hpboatracerman]

Hi Mate, Thanks for your comments 👌 Yep, I put a video up of how I made that lower unit, it’s a few videos ago on my channel. cheers 🍻 Aussie Boat Guy 😎

[@broderickwallis25]

That run by, shore shot with the rooster tail, i thought F*n Donald Cambell mate !!!!

[@25hpboatracerman]

Hi Mate, That’s awesome 👏 yeah it’s hard to film to show what’s really going on but the side shot looked ok. cheers 🍻 Aussie Boat Guy 😎

[@Diesr]

wow thats a knife it looks cool also HOW did you make your own prop thats awesome mate

[@72mardy]

I think he cut down a standard stainless prop

[@Diesr]

i get that but the skill that takes to get it simetrical on a 3 blade thats not to scoff at @@72mardy

[@25hpboatracerman]

Actually made it from scratch and welded the blades on, got an earlier vid on the channel.

[@25hpboatracerman]

Hi mate, I made a hub and cut three blades out of stainless steel. I made a jig to hold the blades on the hub at the angle and rake I wanted then welded them on. Ground the welds then polished. cheers 🍻 Aussie Boat Guy 😎

[@72mardy]

@@25hpboatracerman holy shit, sorry mate. I had no idea, that's awesome. I didn't mean to insult your skills. I'm gonna go find the video now and watch it.

[@brendanbarker2095]

Cool!

[@25hpboatracerman]

Hi mate, yeah, loving it 👌👌 cheers 🍻 Aussie Boat Guy 😎

[@BackyardBeeKeepingNuevo]

Have you considered dropping the motor down slightly more to get a little “cleaner” water?

[@25hpboatracerman]

Hi mate, I did try that but it was slower, will try it again with different trim settings. cheers 🍻 Aussie Boat Guy 😎

[@kyahbwtinnybashing]

seen it out in erina creek the ither day shes quick

[@25hpboatracerman]

Hi mate, she is quick for sure 👌 did I talk to you that day? Only been in Erina creek once about 2 months ago, was it that long ago? There is heaps of small tinnys running around up the coast. cheers 🍻 Aussie Boat Guy 😎

[@kyahbwtinnybashing]

yeah you had a chat to us my mate had the ratpack and another boat was their@@25hpboatracerman

[@user-pj6wb5tm9s]

hey mate ever consider doing bigger motors and putting it on a sea al supa skua

[@25hpboatracerman]

Hi Mate, Yeah, had bigger outboards in the past, having just as much fun with these little ones. Got a big bore 60 merc in the pipeline for another project too. cheers 🍻 Aussie Boat Guy 😎

[@user-pj6wb5tm9s]

@@25hpboatracerman yeah of course just thought a supa skua would be perfect for what you do and yeah that 60 for the haines?

[@Timbuctoo]

I have a 4.8m fibreglass boat with 115hp Optimax, what top speed and cruising speed should I be getting? I get it up to about 40km/H and it alarms.

[@25hpboatracerman]

Hi mate, Firstly check why it’s alarming, I would start with impeller and make sure the thermostat is good and water passages clear. I would say you should be up around 70kph if running ok. cheers 🍻 Aussie Boat Guy 😎

[@jimcrawford8254]

Mate just be careful of the engine mounts you ll understand why they are called the egg beater but keep uo the good work

[@25hpboatracerman]

Hi mate, I fully agree 👍, they are very small and weak on that motor. I am going to make a thrust block to take the load, also I reckon it will settle the boat as well because it feels like the movement in the mounts causes twitching while I’m trying to stee, sometimes, like play in a steering wheel. Thayer for your comments and input, I really appreciate it 👌 cheers 🍻 Aussie Boat Guy 😎

[@Elst78]

I heard that some small tohatsus turn all the way round

[@25hpboatracerman]

Hi mate, yes the 3.3hp, 4hp and 5hp two stroke all spin right round. The 3.5hp four stroke spins right round too. cheers 🍻 Aussie Boat Guy 😎

[@vibratingstring]

Our old Evinrude 2hp was turned round for reverse.

[@willsmith1988]

(On the fly jack plate) would be good for this would be able to lower the prop into the water and get on plane and lift it up

[@25hpboatracerman]

Hi mate, I totally agree and that would be awesome 👏 maybe in the future. cheers 🍻 Aussie Boat Guy 😎

[@mercmanwon]

I’m not sure another 30 lbs would actually result any net net gain. Holeshot is pretty good as it is.

[@25hpboatracerman]

Hi Mate, Yeah, I tend to agree. If I was having trouble jumping up on the plane then maybe worth while but it actually gets up well. True too about the extra weight, I definitely don’t want that. Cheers 🍻 Aussie Boat Guy 😎

[@MrBonito22]

Was wondering if you could give me some advice please? Should the vent on INTERNAL tank on 6 hp outboard be closed or left open when not in use. Motor is kept on boat in marina. Thanks.

[@ReviewsSolutions]

I’d recommend closed when not in use to prevent moisture intrusion.

[@25hpboatracerman]

Hi mate, definitely closed, it’s to stop moisture entering the fuel tank. only vent when in use. cheers 🍻 Aussie Boat Guy 😎

[@MrBonito22]

@@25hpboatracerman Thanks for reply. The reason I asked was because someone told me his external tank expands and distorts in the heat if closed, and it would do the same to internal tank. I think I'll take your advice. Thanks.

[@vibratingstring]

@@ReviewsSolutions In the U.S., the federal EPA foisted a nonsensical California regulation on all portable fuel tanks. The problem is that they expand and then the vapour pressure pushes liquid gasoline out through the threaded fittings and all over the deck. So I put fuel stabilizer in my gas, leave the cap cracked open, and take the gasoline ashore for car if not used in a month. Perhaps your integral tank is capable of taking heated vapour pressure. Read the manual

[@coney207]

Fack'n move'n guy hell yeah 🤘

[@25hpboatracerman]

Cheers mate 🍻 so much fun All the best, Aussie Boat Guy 😎

[@coney207]

@25hpboatracerman love it!!! Cheers bud!!!! 🇦🇺🇺🇲

[@paradiselost9946]

until you hack into the manifolds and strap on a set of pipes, youre missing out... be sorta fun to make a pair :) havent played with 2smoke for a few years...

[@25hpboatracerman]

Hi Mate, I agree and would love to go that way but unfortunately where I live I would get in trouble for noise 😢 Still may happen someday though 😂 cheers 🍻 Aussie Boat Guy 😎

[@paradiselost9946]

@@25hpboatracerman pffft. noise! plumb em back into the leg... or just run em! iunno, i know the standard idea of a twostroke is hearing the yz250 from about 5km away, but all the pipes ive made myself for chainsaws and the like generally come out quieter than stock... often get more intake noise!

[@arturomartin2260]

👏🏼👏🏼👏🏼👏🏼👏🏼👏🏼👏🏼

[@25hpboatracerman]

Cheers Mate, Aussie Boat Guy 😎

[@Junkitup]

Is that the tender?

[@25hpboatracerman]

Hi mate, it’s just a fun little tinny, wish it was a tender to something bigger 😁. I would love a cruiser 👍👍 cheers 🍻 Aussie Boat Guy 😎

[@Gobsmacked22]

Should connect the kill cable to you by clip putting your hand through it like that will slide straight off and do nothing if you come out mate do more nipper videos

[@25hpboatracerman]

Hi mate, thanks 🙏 I totally agree and will sort something better. cheers 🍻 Aussie Boat Guy 😎

[@y4s563]

Nanaimo bathtub racing . You may be surprised at the level of knowledge . You need to make changes ... You will go way faster .

[@25hpboatracerman]

Hi mate, love the tubs 👍 I would not be surprised at all, I’ve raced boats for many years, my friends dad was world champ tubber and my mate still has the boat. The tubs these days run the 9.9hp Tohatsu which as you know is way faster than the 9.8hp (which is the same as the 6hp with some better parts) the 9.9hp Japan built is capable of close to 80kph with its 1.85 to 1 gear ratio along with a winrace prop on a ridiculously light tub. I might try my modified 9.8hp (which is close to 100cc smaller capacity than what they run on the tubs) on a tub and see what speeds I get, I’m estimating 67kph 🤷‍♂️. I may modify a 9.9 or 15 or 18hp next. also keep in mind the 9.9hp Japan built is a de-tuned 15hp so is not too hard to modify along with way more wall thickness on the transfer ports for porting. cheers 🍻 Aussie Boat Guy 😎

[@2200pathfinder]

IS THE BARREL FLARED ON THAT STAINLESS PROP?

[@25hpboatracerman]

Hi Mate, The hub on the stainless propeller is straight, you do not need a flair on a surface piercing prop. Cheers 🍻 Aussie Boat Guy 😎

[@2200pathfinder]

@25hpboatracerman ok I was going to say cut it off if it was.

[@ikanTemperas]

my tohatsu m18e2 engine can only accelerate up to 51kmh... the engine still hasn't been modified just changed to an 11pitch propeller

[@25hpboatracerman]

Hi mate, 51kph on the GPS is pretty good for the 18hp, that’s about what I’m getting with my 18hp on an 11ft tinny with a 10p alloy solas prop. I’ve tried other props including stainless, other pitches but always come back to the 10p solas. cheers 🍻 Aussie Boat Guy 😎

[@vibratingstring]

boat weighs what? You weight what? 9.9 hp? 2 str? Weighs same as an old 15? What? I want to plot your results on to Crouch Curves to compare. Will send you a copy:)

[@25hpboatracerman]

Hi mate, that would be awesome 👏 The boat weighs 34kgs. I weigh 84kgs with shoes, clothes, life jacket etc. The motor is a 9.8hp Tohatsu which weighs 26kgs. I have a bucket of safety gear onboard which weighs 11kgs. the fuel tank and rear ply seat weighs 7kg with 5 liters of fuel (normally what I run with). Cheers 🍻 Aussie Boat Guy 😎

[@wakperantau114]

Nice but your cavitation plate too high propeller suck too much air..

[@25hpboatracerman]

Hi Mate, The GPS top speeds tell me that height is the fastest during many test runs. Cheers 🍻 Aussie Boat Guy 😎

[@alexmechanic7072]

Hello What is the power of your engine?

[@Phantom-mk4kp]

9.8 with port mods higher compression and larger carb plus a little felting

[@25hpboatracerman]

Hi mate 👋 I’m not sure of the actual power of the motor now but definitely more than 9.8hp 😁 cheers 🍻 Aussie Boat Guy 😎

[@mickbrumer]

Surface drive!!

[@25hpboatracerman]

Yep, it’s running nice and high 😂😂 cheers 🍻 Aussie Boat Guy 😎

[@sams7655]

You need to show gps while you're driving that hotrod! Seems fishy that you only show it afterwards. Also add some more gear in it, maybe another person. I suggest skinny tan blonde about 130ish lbs

[@25hpboatracerman]

Ha 😂 don’t have one of those to put in. Fair enough on the GPS, wasn’t really needing to prove anything so had it in my bag as not really anywhere safe to put it. Also even if I show it, I could have two, one with a higher speed set on one etc etc, someone will always say I’m cheating etc etc so it’s really more for me the gps so I can try beat the top speed with more mods. Also if I was one to cheat with top speed gps numbers surely I would say more than 61.1kph. I’m hoping at some stage to get that motor up to 65kph then it will be faster than my stock 30hp 11ft tinny. it’s more for fun anyway 👍👍 cheers 🍻 Aussie Boat Guy 😎

[@jeffarcher400]

I always thought that prop drag was the biggest obstacle to going fast and reducing fuel consumption. I'd try some kind of power trim. Either the motor,trim tabs or both. That'll get you on plane and control hull angle optimizing the hulls contact patch and reducing cavitation. I wish outboards had a closed cooling system like everything else is. Perhaps you could bypass the stock intakes and hook up a motorcycle radiator. Mount the radiator where it gets airflow or put it in a cooler/bait tank with flowing water intercooler. Here in the saltwater it would reduce corrosion and the need for flushing. Sand,mud and seaweed are no longer problems. Now put a foil on the hull and you can be like a flying fish. Just the tip of the tail flicking as you fly above the water.

[@jdrissel]

@jeffarcher400 what about using some aluminum tubing Tig welded to the hull as a heat exchanger?

[@25hpboatracerman]

Hi mate, yeah drag is a massive restriction for speed with boats. with Trim, I want to keep weight down as much as possible so I’m going to make a light trim block so I can optimize the trim setting for top end speed (not too concerned about take off as long as I get up on the plane). A closed cooling would be great but not sure a radiator would cool enough as most outboards run at under 80 degrees Celsius, a heat exchanger would be the go. all the best and cheers 🍻 Aussie Boat Guy 😎

[@lucatimer1234]

I will send to you my Tohatsu 18 hp, and it will return back like a 50hp...😂😂 Ciao dall' Italia 🤟💪👋

[@25hpboatracerman]

Hi Mate, Yeah probably 😂😂 I might do an 18hp next 👍 cheers 🍻 Aussie Boat Guy 😎

[@BurchellAtTheWharf]

No way that's under 10 hp

[@BurchellAtTheWharf]

Gotta love that 2smoke oower😅

[@25hpboatracerman]

Hi mate, Yeah I agreed 😁 I’ve done a lot of mods to that motor - poring, high compression head, custom tuner, intake and reed mods, bigger carb and lower unit etc. Not sure on actual hp but probably about 13hp but happy to rev. cheers 🍻 Aussie Boat Guy 😎

[@BurchellAtTheWharf]

@25hpboatracerman she is definitely a screamer man, and love all 7200+ rpm of glory

[@treeturtle9378]

Centapede

[@25hpboatracerman]

Caterpillar 😂

[@officialWWM]

Do it to a 250hp 😂

[@25hpboatracerman]

Hi Champ, I wish 😂 cheers 🍻 Aussie Boat Guy 😎

[@jacobkaup3571]

At least the bow is down should still be a little flater pretty impressive ill bet you can still do even better had a 35hp on my 14ft aluminum custom aluminum transom motor tilted and a 25# anchor in the front would do 34mph about 3/4 throttle never wanted to go any faster crazy

[@25hpboatracerman]

Hi mate, Thanks for your comments 👍 Yeah, over 30mph starts to feel pretty fast in a small tiller steer boat. Definitely I am going to be playing more with setup to see if I can squeeze more speed. cheers 🍻 Aussie Boat Guy 😎

[@judechopper]

But you don't reply to questions 😢 so it's all about your aboards, not cool

[@25hpboatracerman]

Hi mate, sorry, I do try to reply to my questions. did I miss a question from you? please re-ask and I will do my best to answer it. cheers 🍻 Aussie Boat Guy 😎