If the keel is actually straight, you'll have less of an issue but there is likely still to be some minor tracking toward the bend.

As for the rudder,do you mean skeg or rudder?  If you mean a fixed, unturning skeg, I know the directions I got with my boat had suggestions where to put the skeg.  If you actually mean a rudder for stearing, I wasn't aware there were any that were installed anywhere other than the stern of the boat.

FrankP

I am talking about a rudder like the feathercraft or a Smart.  I would need to cover the hole left by the cut at the back of the boat... I am building a c 17.

.5 of an inch? Only you will ever notice, and it won't noticeably effect the boat's handling. It's not rocket science, and there are hundreds of variables when on the water.

If you haven't glued it all up yet, you can usually just loosen or tighten some of your stitches to get things symmetrical. Have you checked for hull twist, too? See the Boat Builders Tips link for info on that.

I'm not familiar with the rudders you are talking about, but most kayak rudders are designed to fit on the usual V sections at the stern of the boat. If you need a small transom to fit your rudder, just determine the minimum size necessary, and lop your stern off where that measurement coincides. I'd definitely do that last, and only after lots of planning!

Good luck!

Dave Gentry

thanks for the replies...

 like you said I guess only I will know but what about tha assymetry on the sides... should I worry about that?   I am too perfectionnist.

 As for the rudder, I need to do the cut before I fiberglass the boat therefore I need to do it ahead of time.  I'll check with other boats and decide on the width of the stern then and make the cut.  If I need to reinforce it, I'll add pieces and cover with epoxy.

Are you talking about the feathercraft and smart rudders sold by CLC?

http://www.clcboats.com/shop/products/boat-gear/kayak-footbraces-rudders/feathercraft-single-rudder-kit-k1.html

 They are all mounted on top of the deck - no hull mods are necessary, unless it be some holes and/or reinforcements. In any case, what you will need to do to mount your rudder will be explained in the instructions that come with the rudder - I certainly wouldn't start without that.

And, really, only you will ever notice any asymmetry. But, really, you can almost always fix that sort of thing pretty easily - http://www.clcboats.com/shoptips/stitch_glue/checking_twist.html

 Good luck!

Dave Gentry

too late for that my friend... taped, epoxyed and cured... I must have done something while putting the stuff in the cracks or simply touched it by accident or something like that. Can I twist the bow when I attach the deck to the hull?  I don't know if the front is moving when I try to twist it by myself. 

 thanks again for your help.

 A

You've not told us which boat you're building, but I surmise it's a kayak.

It takes a truly shocking amount of twist to actually impart turning moment on the water.  I've never managed to build a boat with enough twist that it wanted to turn.  Builders fret about it though, and it's an aesthetic thing.

Many times, I have erased twist from a kayak by slitting a few feet of the stem/stern/keel with a japanese saw. Slide the hull back into alignment, squirt some epoxy in, clamp it, let it cure.  Works a charm, and no one is the wiser.

Thank for the advice... I may do that!  I am building a Chesapeake 17 soon to possibly be 16.9! LOL  I'll give you guys a phone call for some live advice.

 Thanks again!

 Alain 

My WD12H I thought had a twist to it but I realized that keel was pretty straight. It was the sides of the hull that were trying to collapse, one side more than the other. I tried putting the temp forms back in but couldn't even get close with those. I was putting a level across the hull at several points and it showed a definite twist, bow going counter-clockwise and stern going clockwise. I just starting putting the forms in to start the deck and will wait to see if that tries to straighten it out. The first two were very difficult to put in. It got too late and cold to finish the job. Will get back to it this weekend.