Builders' Forum Archives
Re: lt 17 alterations
Posted by Dave Houser on Sep 22, 2004
I didn’t see your BB message and my email crashed for a couple days and I lost all messages.
A recess on a full size Ches 17 is a very good modification. In fact, if I were to build another Ches 17 it would be the LT with a recess. The main advantage of the lowering the deck at the cockpit is to lower the back coaming to allow lying back on the deck to facilitate rolling. Locally lowering the deck at the coaming is often called rolling recesses it is quite common on strip kayaks.
All kayak designs weathercock, turn into the wind, to some degree. The standard solutions are to live with it, add a skeg, add rudder, add rear ballast, move the seat back or redesign the kayak.
Raising the front keel, lowering the aft keel, raising the front deck and lowering the rear deck all will reduce weathercocking. Moving the Center of Buoyancy (Center of Gravity) back, i.e. moving the seat back, will do all four. I like to have a kayak without the moving parts and drag of a retractable skeg or rudder. A fixed skeg can be oversized and then ground down by trial and error to make a wind neutral kayak but it adds to the tracking thus increasing the effort to turn and stay on course. So I choose to trim the kayak with weight distribution by moving the seat. I installed a sliding seat and now never move it. It remains located 3 inches behind the plan location. I will adjust it in route if I miss balance the cargo weight between the front and rear compartments. I almost always day paddle without cargo. And almost always paddle round trips in the open ocean often dealing with wind and following seas.
Modifying S&G panels is a tricky thing especially anywhere except maybe at the shears. The reason is changing one panel also affects the adjoining panel. This is especially true at panels that have a lot of twist in them like the bottom panels. When removing an inch at the mid length of the bottom panels you are removing a horizontal dimension, at the ends a vertical dimension, in between some horizontal and some vertical. If you remove a varying vertical dimension from the bottom at the chine, how do you know how much vertical dimension you have to add to the sides to match? It becomes a full redesign of the panels. However, the sides on a Ches 17 are near vertical along their entire length so removing a constant amount along the length of the shears will, very nearly lower the deck evenly.
If I were going to modify the Ches 17 design a little I would raise the chine at the bow to make a sharper front keel so it cut through waves and chop and reduce the slamming of the bottom panels when coming over waves. But that is a panel redesign.
In Response to: lt 17 alterations by Scott on Sep 22, 2004