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View Full Version : Chine Logs in clinker plywood?



DeniseO30
02-24-2009, 09:57 AM
Just doing some thinking with my fingertips again :rolleyes:. It occured to me, are chine logs needed or used in plywood dories? I'm thinking of the glued lapstrake, to the garboard/ floor. I know the the angle is pretty steep and epoxy glue is stronger then the plywood but...

then I'm thinking it would be easy to plane the bottom of the chine logs and glue/screw the floor to it rather then bevel the floor edge and affix the first plank to it's edge. (building upside down)

Jim Ledger
02-24-2009, 10:15 AM
Do you have plans? If so, what do they call for?

TerryLL
02-24-2009, 10:48 AM
I'd like to see the plans, but most of the epoxy-ply dories I've built did not use chine logs. The bottom is usually twice the garboard thickness, resulting in a wide gluing surface. Smaller dories as a rule, either ply or solid lumber, do not use chine logs. Plans for larger ply dories, in the 22'-27' range, often use a chine log.

mcdenny
02-24-2009, 10:49 AM
You would certainly need a reinforcement at the side/bottom joint. It can be 1x2 (or larger) wood or a generous fillet of epoxy and fiberglass tape.

My choice would be the wood - much more plesant to work with and will give a neater appearance in the finished boat.

I agree that you should orient the long dimension parallel to the side and plane a bevel onto the edge that fastens to the bottom. 000s of boats have been built this way.

Terry's post popped up at the same time as mine -so I need to add I am talking about both sides and bottom being plywood, not so good for edge fastening.

Thorne
02-24-2009, 10:51 AM
Most dory plans, either for trad materials or ply, don't call for chine logs as far as I know. The frames, either bent or sawn, combined with glue seem to do the job of holding the bottom onto the garboard strake. Of course you don't want to screw into the side edge of a ply bottom...

As Jim asks, what plans and/or design?

TerryLL
02-24-2009, 11:10 AM
You would certainly need a reinforcement at the side/bottom joint. It can be 1x2 (or larger) wood or a generous fillet of epoxy and fiberglass tape.


I have to disagree here. The bottom-garboard glue joint in an epoxy-ply dory needs no further reinforcement, just as the lap joints need no further reinforcement. In fact, because of the width of this joint, the garboard-bottom glue joint is likely the strongest lap in the hull. Take a look through The Dory Book and you will not see a single chine log.

DeniseO30
02-24-2009, 01:08 PM
Just doing some thinking with my fingertips again :rolleyes:.

I wasn't referring to anyone's plans. I just thought that it could be a problem with lightweight plywood. The chines on my S & G clc kayak have never had a problem but then a Dory is going to be beached and knocked about more then a kayak. I must say that I never really liked the look of a filled joint in a bright finished interior though. When I finally get around to building my "Gardner Car Top Semi-Dory" I'll know first hand if I want chine logs. It does seem they would allow floor board fitting somewhat easier.
Love the input! thanks!

TerryLL
02-24-2009, 04:21 PM
Always a good idea to FG tape the outside bottom seam on a clinker ply boat to really seal up the exposed end grain. I generally FG the bottom and up to the first plank lap. The lap is a good place to end the FG because the FG edge is concealed up under the lap, and the only fairing needed is right up at the bow.

Oughtred's book on clinker-ply boatbuilding is a great reference.