Bucket Placement In A New Ski?

Hi All,
I am currently building a wood strip ski which is based on the current Epic V10L. I have made some minor changes including a bit more beam. Warren Williamson, a local designer and CAD whiz, entered the rough sections I sent him and modeled it in RHINO. The hydrostatics that RHINO produced indicate that the bucket would ideally situated around 40mm forward of the position Epic places theirs in the V10L. They obviously know what they are doing but I also know they have to make a call based on an "average" paddler. We all have a slightly different CENTER OF MASS and I am basing this on my particular CM. This stuff is part science, part voodoo and part art. I have noticed that as new models of skis come out the bucket and rudder positions will sometimes get tweaked. My inclination is to split the difference but I realize there are many of you out there with more knowledge and insights than I have. Any thoughts or feedback from the community would be greatly appreciated.
Here is a link to the ski I built last year if you are interested.
www.surfskiracing.org/2014/12/building-w...n-surf-ski-ken-katz/
Ken

Nice design. And the ski from last year looks great, but that was already in my bookmarks.

Can't you have a test paddle without the bucket, just sitting on a piece of foam? Not in the rough stuff of course. This would enable you to have a visual check on the trim.
It has been a trend to move seats forward, the second generation Stellars did, and if I am correct some of the EPIC 2gen as well. So I would be tempted to just use the 40 mm ahead position.

For the kids ski design I am working on I might try to incorporate a sliding seat, kind of K1 seat with as much of the volume around it filled to avoid a lot of water in the bucket.

If I may ask, what is your CAD guy using to calculate hydrostatics in Rhino? I do the base design including hydrostatics in kayak foundry, and the final tweaks and bucket in Rhino.

The ski is very lightly built so it would probably be a bit flimsy to try and paddle it without the deck. I will pass your question on to Warren. Thanks for the input.

Some people join deck and hull first, and make and fit the bucket afterwards. Then it should not be to risky to do a test paddle.
If you fit the bucket to the deck before joining hull and deck, it will be obviously a much more flimsy affair when you do a test paddle. And due to the flexing of the hull it might give incorrect results anyway. So in that case I would not bother about it.

Regards,

Merijn

In case you missed it, in a recent post this came along (check posting 25123):

www.surfski.info/forum/19-boats/18557-un...ellar-sel.html#25123

So 40 mm ahead is considered desirable by more people. For what it's worth.

Regards,

Merijn

Merijn,
Thanks for the input. The V10 is a different hull than the V10L but it is food for thought.
Cheers,
Ken

I'm 185 and paddle primarily downwind in bigger stuff, so take this for what it may be worth.

I'm in a new V10L now and love it.

My previous boat was a V10, which was referenced in the link provided by merijnwijnen. I needed to move forward in the cockpit to make the boat run better. Incidentally, Epic did just that with the old model V10L. Two inches as I recall. Anyhow, I had a composite seat made that moved me forward almost an inch. It lifted me up almost an inch too. The change was very good for me. Minor loss of stability that went away in a day or so. Much, much better downwind. That boat would fly on big swells. But I got tired of taping the seat in, so I moved on.

Went to the new V10L for the comfort and extra stability. A bit slower, but much more fun. My stroke needed the stability in a big way and is markedly improving.

Personally, I don't feel a need to move my weight forward at all in this boat. My guess is that Epic set the center based on the average paddler in all conditions. They probably had to shift the seat back a bit to help us heavier paddlers in larger conditions. I jam that nose deep (big mistake, but it happens) and lean way back on occasion. I'm happy with the seat fore/aft placement.

IMO, I'd move that bucket forward in your wood boat if you do primarily flatter water. I'm guessing a K1 design would have the center of mass very close to the center. Just a guess. Those boats don't want to push water. I don't mind slogging on flat water because I need the stability in my conditions.

My other suggestion would be to try and scoot forward in an L and see how that feels (and appears from the side on video). The hump will be an issue but at least you will have some more info. I agree that designing skis is a healthy dose of black magic. 40mm is a big move. As is adding beam to the design. Best of luck.

Yikes, that wood boat is just amazing. On so many levels. Great work.