Builders' Forum Archives
Posted by Dave Houser on Dec 20, 2004
When evaluating a kayak design, weathercocking can be reduced by making the bow higher, making the stern deck lower, raising the front keel or lowering the aft keel. Moving weight back does all four.
Most factory kayaks and kit designs seem to weathercock and the weight and girth of the paddler also has an effect. So the quest to trim a kayak is there for many.
To reduce weathercocking without modifying the boat is what you have done to date, moving the seat back and/or adding rear ballast. Since you have moved the seat back as far as it will go and that is not enough and adding ballast is not desirable then it is time to modify the kayak.
The easiest mod is to add a fixed skeg. The farther back one is installed the smaller it will be. Most guys will tell you to install one a foot forward from the stern. The rational is to keep the skeg in the water when the stern lifts out on a passing wave to avoid broaching. I do not agree with this because broaching in my kayak occurs while surfing down the face of a swell when the bow keel digs in deeper and the aft keel is also buried. On the crest of the wave when the stern lifts out the extra maneuverability is a welcomed opportunity to correct direction. Anyway, glue on a skeg near the stern. If you make it oversized your kayak will leecock (turn downwind) and then carve the skeg smaller, using trial and error, until the kayak becomes wind neutral. Beware that paddling a leecocking kayak is worse than a weathercocking kayak and considered dangerous so do the trial and error testing in a safe controlled location (not 5 miles out to sea) until the skeg is properly trimmed to size. The big disadvantage of a skeg is it adds tracking. So now the kayak does not weathercock but when corrections are needed it will require more effort to turn the kayak. Edging, sweeping, bow rudder, stern rudder or draw strokes all have their place but edging and sweeping together are the norm.
If you want a mod with no moving parts and without increasing tracking you have to move the seat back more. Yes enlarge the cockpit back. If you also have to move the rear bulkhead it really gets involved. (I lengthened the coaming back 2 1/2 inches, to the bulkhead, on one of my kayaks and still had to add a small fixed skeg.) When building a kayak I rough cut an undersized cockpit opening and test paddle the kayak, in a brisk crosswind, to locate the seat then install the coming to match the seat location. (On my standard Ches 17, I moved the seat 3 inches back from the plan location.)
Adding a skeg box is a good solution. A deployable skeg is dialed in to match conditions and the loading of the kayak. When paddling into the wind you leave it up to have the weathercocking assist in maintaining heading. Paddling downwind you put it all the way down to leecock to assist in running with the wind. In a crosswind and/or quartering swells you partially deploy the skeg to balance out the wind/wave effect. Deployable skegs should be spring loaded so they can be pushed up without damage by an encounter with a rock. The advantages of a skeg are 1) a clean stern for self rescues, 2) solid foot rests for bracing, 3) fewer moving parts than a rudder, 4) you still learn to steer with your paddle. Disadvantage is there is a beach out there somewhere with sand pebbles that are just the size that will jam it in the up position.
The most common solution is to add a rudder. Advantages you can steer all the time and maintain your most efficient forward stroke. Disadvantages 1) they are an effort to build, 2) when up they increase weathercocking so you will use it often, 3) they snag seaweed so they should be spring loaded, 4) they are no fun to crawl over during a self rescue (no cowboys for you), 5) they are vulnerable to damage, 6) they are expensive to buy, 7) they create soft peddles that compromise bracing and rolling, 8) they often retard development of paddle skills and 9) they can cause injury to out of boat paddlers in rough water or in the beach wash.
Pick the mod that matches your paddling style and your ambition to modify your kayak.
In Response to: Seat Placement by Mac on Dec 19, 2004
- Re: Weathercock Correctio by Mac on Dec 20, 2004
- Re: Weathercock Correctio by Steve on Dec 22, 2004