Looking to discuss set up for towing head high+ waves. Seems we are lost in tuning for the wide speed range that comes with bigger wave towing. Trying to tune a P140 with shunt 14” tail pack on a Kalama E3 3’10” board. We are all between 190-210lbs.
Our wave goes from low and fast to standing up then backing off. This can go on for a mile+. Seems we are dealing with back leg fatigue and would like tune that out. Seems like the simple move would be to positive shim to add front pressure. Problem is on the fast sections we are already dealing with overfoiling. Sometimes we are overfoiling on smaller jacking waves as well. My first thought is a smaller front wing which I’m
sure would help but I’m still trying to understand the tuning part.
My goal here is to open a discussion that would explain the basics of tuning for large speed ranges, higher speeds and bigger waves. We are intermediate+ riders so I’m sure there is some skill that needs to be developed in addition to understanding tuning.
I’m curious to know what my mast should be for prone foiling does it depend on the wave size and my foil choice? So I can adjust the amount of lift I want? With the goal of moving it as far forward as possible?
If you are getting over foiled and can’t keep the front wing from breaching, then it seems you need a smaller front wing. I would highly recommend the Lift 70HA for tow foiling. The 70HA turns so well, it feels like a shortboard! The 70HA is also very pitch stable, which makes it easy to plow through the swell when you’re getting towed around looking for a wave.
For dealing with back leg fatigue, you need to counter the forward pitching moment at higher speeds which is causing your front wing to dive down, which then causes you to put more weight on your back foot.
To stop the wing from diving down, you need to use more shim to increase the angle of attack on the tail wing or use a bigger tail wing or use a longer fuselage.
I’ve been towing a lot the past few months and had to deal with similar problems with burning out my back leg. I referenced KDMaui’s shopify page to fix my problem,
For prone foiling, I adjust the mast to make the lift manageable on takeoff. If the mast is too far forward on during takeoff, you end up getting ejected. If the mast is too far back, you might pearl on takeoff.
KDMaui likes to adjust his mast position based on how the foil behaves in a turn. See the KDFoils foil info link in the above post.
I saw the post and it makes sense to check it it’s too high or low on turns as well as the takeoff it.
What do you mean pearl on takeoff, you mean u cant generate lift and your board is just planing on the water but ur not flying?
. I already am adjusting to the conditions, if it’s small waves and I got a small foil, then all the way forward, if I have a bigger foil for the wave then back so I don’t get ejected. I haven’t figured out the benefit or con of the position besides whether or not I get ejected and overfoiled on takeoff. I guess the rule of thumb is as far forward as you can as long as the takeoff is easy and manageable… if u wanna catch a bigger wave then move it back slightly
@JonnieTyler Thanks for the applicable explanation. That’s exactly what I was hoping for when I generated this post. I think I almost have a grip on the concept.
Would you say there’s a difference between the lift affect from over foiling and positive shimming?
In my head I’m afraid to positive shim (to reduce back leg fatigue) if we are overfoiling at higher speed. Wouldn’t the positive shim increase lift at speed?
From my understanding of foil theory, the center of lift on the foil will change as your speed changes. At a certain speed, the front foil is lifting and you have to increase front foot pressure to prevent the foil from breaching. Once you go fast enough, the foil will want to dive. If the back wing is too small/fuselage too short to counter act the diving action (the forward pitching moment) you will have to transfer weight to your back foot prevent the nose from diving.
If you can’t stop the front wing from breaching, then you need a smaller front wing. If you can stop the front wing from breaching, but your back leg is burning out, then get a bigger tail or increase the shim to increase the front foot pressure.
To me the P140 felt a little divy at max speed, so you have to use that back leg to counter it. I felt that fairly early in terms of wave size, hip high and above in high period swells.
Head high+ I would say go tiny front wing if you can, 600-800cm^2 will work great. Cab 650, small Eagle/sk8,… Add to that a longer fuselage, it will make the rig more pitch stable to deal with high speeds.
High aspect usually brings more speed and glide at the cost of more span, so those far reaching tips go through the turbulences and destabilize the rig, especially when choppy.
If you need the glide for proning or light wind winging then the compromise might be worth it and go for high aspect.
Otherwise I think mid aspect ~8 is probably a better tool for the job, as long as you size it correctly. You have less glide and less speed range, but it feels more compact and robust in the critical parts of the wave.
There might be an exception to the above which is high aspects with a span inferior to ~80cm, people seem to love them in big waves too.
That’s a good explanation which sounds like our issue we are trying to deal with. Thanks for the lesson in foil theory. I’ve have been treating lift as a liner force with speed, which I now know was wrong.
Sounds like we need to try the vyper 90 or wait for the P100 to materialize. If anyone following has some insight on these two foils, please share. I’m worried we jumped on the progression train without considering our actual use and conditions.
Also around 210 lbs and have not towed my P140, but it does become too much wing on big drops in prone paddling 6ft+. My V130 is way more manageable (and less scary) in size waves. I know a few big guys including the designer that tow the V90 and rave about it. P125 coming next, don’t know of a P100.