Short or Long Mast for Pumpfoiling - What to Consider

Many people are wondering if a short or long mast should be chosen for pumpfoiling.
In this video, I will discuss some aspects to consider, when deciding for the ideal mast length for your pumpfoil set.
00:00 Introduction
01:07 Mast length of different brands start sets
02:30 Definition mast length
03:07 Impact wave conditions
03:57 Using the mast for different foiling sports
04:16 Is a long or short mast more difficult for pumpfoiling
04:50 Impact of the mast length
06:43 Calculation of the impact of the mast length
08:32 Interpretation of the calculation - how a short and long mast compare
10:22 Aspect of dock height
10:58 Summary

[@bensthingsthoughts]

Clearly a video made by a former ETHZ student ! I have PTSD of 1st year physics exams watching this ! Greetings from lake Neuchatel

[@philipp4u2_thefoiler99]

You unmasked me😉 The times of physics lectures at ETHZ Hönggerberg… luckily, studying mechanical engineering, I only had one physics exam needed for my diploma😅

[@foilenvie]

Great Video and explanations ! I have experienced an additional effect of Mast Lenght. If the board is at the same height above the water with 2 different masts (which is what naturally happens when you change mast height), then the longer mast is deeper in the water. As the nearer the foil to the surface, the more efficient it is, the deeper it is the less efficient it is resulting in a reduced pumping time.

[@philipp4u2_thefoiler99]

Hi, happy to hear that you like my video. Interesting topic and I already tried to find some physical explanation for that because I experience the same. I guess the main reason is that when you have "more of the mast" in the water, you will also have more drag from the mast which I guess we perceive that it is less efficient. May there are also some effects that the density of the water is increasing with more depths, but I doubt if we can really feel that due to these few centimeters. But will try to dig deeper into that 🙂

[@foilenvie]

@@philipp4u2_thefoiler99 I think this has something to do with the amount of water above the foil. The deeper it is, the more water and therefore weight there is above the foil when you try to have it go up.

[@philipp4u2_thefoiler99]

@@foilenvie Thanks, interesting thought. Have not considered that before as the flow around the foil is generating the lift, however have to look into that - thanks!

[@123jacquesattaque]

Thanks for the interesting explanation, very useful! I think that the increase in water density at depth is negligible due to the (nearly) incompressible nature of a fluid. What we experience is the added pressure due to the weight of the surrounding water, which increases linearly to the increase in depth. As a consequence, we will not increase lift by having the foil deep in the water, only more drag on the mast and possibly some effect by the increased pressure on the pumping cycle (not sure about this last part). And to add, in salt water, the density is higher so we experience more lift at the same depth as compared to fresh water... @@philipp4u2_thefoiler99

[@123jacquesattaque]

And of course, you have the different mechanical properties of masts of different length (torsional and lateral stiffness). All things being equal, shorter masts will be stiffer in both aspects, thus increasing control over the system (a very light-footed analysis, I know). This also plays a huge part in controlling the system. But I guess that is a topic for another video:)

[@barbaracristina488]

Thank you so much! Best explanation I could find🤙😊🌊🏄🏻‍♀️

[@philipp4u2_thefoiler99]

Happy to hear that you liked the explanation. I will also try to do some more videos. Please feel free to subscribe so you get notified about new videos and explanations: kzbin.info/door/sNgFH9DNNeP4nmNocjyYAQ

[@linuskoppel1535]

another great analysis and explanation video 🤙😎

[@davidstewart9982]

Thanks for this analysis,!

[@philipp4u2_thefoiler99]

You are welcome! Happy to hear that you like it!

[@pkundrat]

Nice analysis. Might be also useful to mention how longer/shorter mast affect complete begginers at your courses and what length you recommend for them.

[@philipp4u2_thefoiler99]

Hello @pkundrat, great that you like the analysis and your comment. May I could have highlighted that more. Will consider that for new videos. I mentioned that indirectly in sectio n "04:16 Is a long or short mast more difficult for pumpfoiling" A longer mast is more agile and perceived as less stable. I think a mast around +/- 75cm is ideal for beginners. That is also the mast length I use most in my training courses.

[@maksymskoryk3784]

great work!

[@philipp4u2_thefoiler99]

Thanks a lot, great to hear that you like it

[@Switzerland1291]

Danke Philipp. Guet erklärt und animiert 😃

[@philipp4u2_thefoiler99]

Danke, freut mi wenns hilft! Vill Spass bim Pumpe!

[@Subscribe2Glide]

I love to long analytical videos. Maybe one about mast shims, fuse shims, front wing shims, rear wing shims. I have noticed that a negative fuse shim gives me more forward thrust during pump and reduces drag during climbing.

[@philipp4u2_thefoiler99]

Thank you. I was also thinking about doing a video about shims. But hadn't had time so far, but have it on my list! Thanks for the input!

[@Subscribe2Glide]

​@@philipp4u2_thefoiler99after a lot of testing, i now use a 2 degree positive mast shim for increased angle of attack and no rear wing shim, i plan to test a negative mast shim next. Love your mathematical approach to pump foiling!

[@frasershaw3071]

I understand the increased drag of a longer mast - what I still have not figured out is the effect of conservation of angular momentum. In my mind - for a fixed rotation speed the foil must travel slower thru the water than a short mast does, but crucially the foil travels further so may generate more lift in total ( provided you have overcome the surface friction and have actually taken off ). I think if you have the power and technique the longer mast can be better - if you are struggling to take off shorter is better as there is less drag AND you generate more foil speed.

[@hiltithedrill]

Awesome nerdy video exactly what i was looking for. One question remains, though: can you pump longer/is it less exhausting to pumo with a longer mast as the force generated with the same tilt angle is greater or does it not matter at all? 🤔

[@philipp4u2_thefoiler99]

Hi, happy to hear that you like the video! Well, really good question. I would say it does not matter too much as the tilt angle changes during the pumping cicle from + over 0 to - position, so lesst impact due to that comparable to other factors that influence for how long you can pump (rhythm, position on the board respectively position of the body and how you transfer the mass energy of the body onto the board, ...). However, what you will have with a longer mast is a longer glide phase - while going from the highest to the lowest position - which you can then use for relaxation...

[@philippemartin9690]

Great effort at explaining the difference between a longer and shorter mast. Thanks. But is it possible that with a longer mast since you are higher above the water and driving the board down that you generate more power and therefore also more speed? What do you think?

[@philipp4u2_thefoiler99]

Thanks for your comment and great that you like the video! Well thanks to the longer lever you may can get a little bit more quick-energy into the system. The increase in the speed / accelleration is for a great amount coming from the energy you 'inject' into the system, means the moment when you push the board with the backfoot from the downwards to the upwards movement. However, I think that the longer lever is very small compared to what impacts the power you inject in the system. But may some others here have some experience? May I have to try it myself and do some calculations around that...

[@gazmanator77]

@@philipp4u2_thefoiler99 Thanks for the video Philipp. I agree, the energy that goes into the downward speed because of a longer mast has to go into the energy to rise again to the top level that it originally came from. (First law of thermodynamics.) so the only energy difference in reality is that you have a longer glide time and can relax But then you need to get back to the top which needs the energy again. Its all very theoretical, but extremely interesting. I have a 75 cm Indiana Mast but am changing to a 85cm Carbon Indiana and a 1200 har. Only because I can get a 85 cm for a very good price …Unfortunately too many variable there to compare directly. But I will keep watching your channel. Maybe see you in Zürich some day. Greetings from Bremen in Germany.

[@Subscribe2Glide]

Do a vid on positive mast shim

[@philipp4u2_thefoiler99]

Hi, here it comes: kzbin.info/www/bejne/iqDKn2qYa71msKs - hope it helps!