PDA

View Full Version : Build Method for Sailing Kayak/Canoe



ShagRock
01-26-2009, 03:11 AM
I'm planning to build a 14' - 16' wooden kayak/canoe that will be an imitation of a southeast Pacific type with outriggers. I'm debating as to whether to use marine plywood with a hard chine approach or to strip plank to achieve a semi-rounded hull effect.
1) Can narrow planks of marine plywood - 1"wide for discussion purposes - ripped from 4 x 8" sheets with a track saw, be bent on ribs effectively?
2) If 10 plywood planks were used, could they be as easily bent and fastened to longitudinal stringers as opposed to gluing on chine logs?
3) Since red cedar is getting costly for good quality, would a good substitute be western spruce?

Appreciate any and all feedback!
Shagrock

Pernicious Atavist
01-26-2009, 08:29 AM
Do you plan on glassing the wood? If so, the narrow plywood strips would do fine, I'm sure, especially since the gaps would be filled by epoxy.

I think you'd find a more rounded-chine hull easier to sail in waves.

Other will be along soon to add their opinions, so take these all as a group and decide what works for you.

botebum
01-26-2009, 09:05 AM
It doesn't sound like you've decided on a specific plan or designer yet. Or were you planning on building by eye? If you haven't built many of the same type by plan in the past I think it would be a tragic mistake to do so.
Choose a plan that meets your wants, needs and skill level and build it the way the designer suggests.
My .02

Doug

TerryLL
01-26-2009, 09:37 AM
Shagrock,
It's usually not very productive to discuss alternate building techniques unless we're talking about a specific design. Many designers include advice in their plans about different construction methods. So, pick yourself a plan and bring it to the forum with your questions. You're likely to get good answers you can actually use.

ShagRock
01-26-2009, 10:47 AM
Thanks for the feedback so far, particularly Ed's information on the plywood strips and the round hull relation to sailing. Doug and Terry, I am creating my own design - that's part of the challenge and fun too! In earlier years, I helped built a few wooden boats in Newfoundland and even cut all the trees, including the 'crooked stems'. As to 'eye design', many local fishermen boat builders have created real nice boats, with only specific plans for the station molds. My query on plywood was due to not having used it as material for boats. I realize times have changed and even some locals in the fishing villages are using purchased plans and kits to build recreation sailboats.

I have done about 75% of the plan on paper so far. If I find it necessary, a friend has offered to input files in CAD and print out offsets for station molds.

For reference I'm using some hand drawn views of a paraw from a Filipino artist, free Guillemot plans for a sea kayak, specs from an Inuit kayak, and information from Gary Dierking's designs.

With all that in mind, one specific question is working out 'exactly how round or semi-round' works best on a sailing canoe at amidships, and what constraints this will have on the choice of building materials? Aside from marine plywood and western red cedar, what others woods make reasonable planking material for a canoe/kayak?

May your big jib Draw!
Shagrock

Dan St Gean
01-26-2009, 11:22 AM
With all that in mind, one specific question is working out 'exactly how round or semi-round' works best on a sailing canoe at amidships, and what constraints this will have on the choice of building materials? Aside from marine plywood and western red cedar, what others woods make reasonable planking material for a canoe/kayak?

Shagrock

Having built a Gary Dierking Ulua and now messing with a double canoe design in plywood, I can tell you that they are a blast. Gary is quite helpful and a wealth of knowledge. I personally like to have a big volume ama because I like to use the tramp a bunch, but there are are lots of reasons to use low volume outriggers like everyone does in the pacific. I like a bit of freeboard (like 24" of overall height--depending on draft) I also like decking the canoe so I can singlehand without doing the bailing, steering, and sailhandling. A bit more freeboard might also solve that bailing problem, but it's all good. Slim canoes are the norm. Buy Gary's book and you'll have 3 plans and a bunch of useful information for a great price! Slim canoes are critical for getting multihull type speeds.

Dan

ShagRock
01-27-2009, 06:41 AM
Dan, that's encouraging and I will pick up Dierking's book. I did not realize there were a number of plans included. Thanks for your input from your sailing experiences and best of luck with the new design!

Maybe I should be specific re the 'close to' rounded hull on a sailing canoe. If a beam measure at waterline was say 24" at midship and the depth of displacement below the water line was say 6" at the keel line, what number of plywood strakes would be "reasonable" to achieve said 'close to' round bottom without pushing the 4mm plywood into 'fracture mode'. Maybe some experienced boat builders or wood workers have a ballpark answer for this?

ShagRock

Hwyl
01-27-2009, 07:20 AM
Hard chine designs, say three planks per side add very little wetted surface, less than 5%. Chines are currently in vogue for sailing boats.

You talk about "fracture mode" but look into Tornado catamarans which were originally built using 4mm plywood in "torture mode".

Have you seen Dierking's videos on Utube http://www.youtube.com/watch?v=a4FADWXmuHk&feature=channel_page

JimD
01-27-2009, 10:25 AM
Hard chine designs, say three planks per side ...

I like this idea, too. Or more planks if you like. But keep them a few inches wide, at least. You can arrive at a really shapely boat with a few panels per side, such as

http://www.pygmyboats.com/images/Taiga.JPG

I wouldn't use narrow 1" strips of plywood. If you want to go that narrow then strip it properly with cedar. Also, some designers call for longitudinal stringers, essentially chine logs, at each chine for the panels to land on to help keep the shape fair, but a lot of longitudinal stringers will complicate things, and make it more expensive, too, as you'd have to use high quality wood for them. I would loft it up as a multichine, cut out station molds every couple feet, and make panel templates from cheapo door skins. Then when I had the cheapo test panels all worked out and fitting properly, trace them onto good marine ply and wire stitch or tape them in place with masking tape on the outside, and glue them together on the inside.

Here's how I did it with a kayak of my own design (more or less)
http://im1.shutterfly.com/media/47b7cf30b3127ccec2c3b6cc27ce00000010O00CbOGrVu4cMQ e3nw8/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/


http://im1.shutterfly.com/media/47b7cf30b3127ccec2c2a6b186c700000010O00CbOGrVu4cMQ e3nw8/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

http://im1.shutterfly.com/media/47b7cf30b3127ccec2c29fb8477a00000010O00CbOGrVu4cMQ e3nw8/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

http://im1.shutterfly.com/media/47b7cf30b3127ccec2c3cf0867ae00000010O00CbOGrVu4cMQ e3nw8/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

http://im1.shutterfly.com/media/47b7cf30b3127ccec2c39812a63700000010O00CbOGrVu4cMQ e3nw8/cC/f%3D0/ps%3D50/r%3D0/rx%3D550/ry%3D400/

Dan St Gean
01-27-2009, 11:56 AM
Dan, that's encouraging and I will pick up Dierking's book. I did not realize there were a number of plans included. Thanks for your input from your sailing experiences and best of luck with the new design!

Maybe I should be specific re the 'close to' rounded hull on a sailing canoe. If a beam measure at waterline was say 24" at midship and the depth of displacement below the water line was say 6" at the keel line, what number of plywood strakes would be "reasonable" to achieve said 'close to' round bottom without pushing the 4mm plywood into 'fracture mode'. Maybe some experienced boat builders or wood workers have a ballpark answer for this?

ShagRock

You can get a completely rounded shape with torturing a 4mm plywood, go with a multipanel shape, or strip it with cedar. Stripping it is best for certian hull shapes, but it is a bit time consuming--but worth it if you want to keep it clear finished.

There is a plan for a multichine shape by Selway-Fisher at
http://www.selway-fisher.com/Opcan17.htm
if you scroll down a bit.

Either way, it a fun boat to mess with. At 24" wide, you might consider going longer than his 18' Waka ama to his 24' Tikopian. that keeps one sorta slim at 10:1. You can see that a four panel per side gives quite a rounded shape with ply.

I don't know if they still offer it, but the Gougeon brothers of West epoxy fame made a tortured ply outrigger canoe and had plans for it. That would be really cool too--and light!

Dan

ShagRock
01-28-2009, 04:57 AM
Hwyl - Thanks for the references to the Tornado and the Dierking video. JimD - your pictures are appreciated and especially the final product! I really like your neat strongback design and your sharing of the setup for the build stations. And Dan- thanks for the link to Selway-Fisher and Gougeon brothers. At this point, I think I should read up on some of your guys' suggestions and get back when I am ready with some decisions.