<> Wood selection for the hull | Kayak Forum

Wood selection for the hull

Submitted by Scott Maschino on Mon, 07/23/2018 - 22:39

I haven't built anything yet, but have been kicking the idea around for several years now. I've done a lot of looking, reading, watching and such. I understand that the "traditional" hull wood is red cedar. I tend to not follow tradition.  I have the opportunity to fell and mill some black walnut and should be able to get some long, straight 8/4 planks. Reading the bark, I have strong hopes that they should yield some long clear grain sections that could be used in a kayak. As well as a few sections that will likely have some curl. I understand that it will be heavier than a cedar strip build  but I am interested in trying it  

Thoughts on building a strip kayak out of walnut? How will the additional weight effect handling? Will the walnut still be flexible enough to handle the strain of use in rough water? 

DonTaylor1

Tue, 07/24/2018 - 00:19

Scott,

Cedar is used primarily for its bending properties, lightnessand ease of fairing.  Using 3/16  thick strips can help with both reducing addtional weight and bending  properties.  I have only used walnut in an accent capacity.  Almost any wood can be used with enough patience and heat/steam.   Having done highly curved oak accents on a kayak,  it just takes more time and more clamps.    

The additional weight of using walnut over cedar will not affect your handling very much unless you are planning a very low volume kayak that is, because of design, loaded to maximum weight already. Your epoxy and cloth are a fair portion of your weight. 

Cedar also absorbs a little resin which gives a strong bond  to the glass. Many kayaks have been built of other woods, do some more research  in the forum archives and internet. 

You can also join strips on the kayak if the clear material is less than your sheer length. 

 Once encased in epoxy the wood flexes very little as it is sandwiched between two layers of resin and epoxy.  Your wood selection will matter little in this regard as the boat does not really flex in the water.  

Don

 

 

   

 

JohnAbercrombie

Tue, 07/24/2018 - 01:06

Scott:

Don's comments are excellent; I won't repeat them but I agree 100%.

I'll add a couple of thoughts:

Cedar is also quite stiff, which means that the strips don't sag or bend off-line between the molds. And the stiffness of any strip varies with the cube of its thickness, so making strips thinner results in a noticeable change in stiffness. So you won't be able to control the weight of wood in the boat by making the strips thinner, without making the construction more difficult.

Walnut is almost double the density of cedar, so your boat will be heavier because of that. If this is your first strip build, and first project with glass and epoxy, the boat will probably be heavier than one made by a very expert builder (not me- I've never made a very light boat; they are usually in the 40-50 lb range). It's not difficult to make a 60-70 lb kayak! More than one builder has done this, but not talked about it much!

It's not a problem having a heavy boat once you are on the water, but carrying it to the launch and getting it on and off the vehicle, you will be glad for every pound saved. And, if you are going to add weight to the kayak, putting it in the skins (glass layers) rather than in the core (wood) will give more benefits in durability and strength.

That said, walnut is beautiful wood, especially when curly - I've built a few guitars with it. And it's more fun to build a boat with lumber you have milled and dried yourself. (Are you willing to wait until those planks are dry before starting to mill strips for your kayak? :-) )

Nick Schade - …

Tue, 07/24/2018 - 08:46

It is heavier than cedar and is rarely available in long lengths, but if you are OK with that, it works well.

Below is my Nymph canoe with walnut along the top. I used 1/8" thick strips to keep the weight down.

Note that the deep color of walnut can fade over time.

Nymph Woodstrip Canoe

 

I use walnut for accents and really like it.  I use a lot of different woods and still come in at the 35 to 45 pound range but I am careful not to use a lot of heavy wood.  Unless it is Peruvian walnut it will fade over time.   I live in a hot area so I would not want a large span of dark wood to capture heat but I like to accent and define with it.  On my last build I used thermally modified tulip (poplar) and have liked it, it gives the rich brown color like walnut.  I went all out on wood types on that boat (last picture) .  The hull is Basswood (Linden) and tulip, the stems are cherry and hickory, the deck is western red cedar, basswood, tulip, and aspen, the handles are cherry.  The color of tulip is more stable than walnut and the wood is comparable to cedar in weight .

Walnut accent

Walnut accent

Walnut accent

Walnut accentLatest build

Fully prepared to wait for then to dry. I don't want to rush that either by dropping it in a kiln. I figure I would try rough milling some strips as well, stacking and sticker, and see how long they take to drop moisture  as well as how they handle working after they do. Clearer wood will be preferable for that, but the figured wood is what I really want to be able to bring into the design  

Scott Maschino

Wed, 07/25/2018 - 01:55

Thank you all for your responses. I've been kicking the walnut selection around for awhile. As a woodworker, it is one of my favorite to use in my furniture builds. I know that it will fade over time. I plan to use epoxy with UV blockers as well as keeping it covered while not in use. I too am in a hot climate, central Oklahoma, and the summer sun is brutal here. I'm planning to move to the PNW in the near future though so that will help. I plan to build a larger kayak  17+ ft. It will be used for longer excursions of up to two weeks, so being able to haul extra gear will be a must, as well as being able to handle longer passages through the fjords in BC and SE Alaska.

As far as being able to source long boards for the build  I'm not overly concerned there. The trees we are looking at are quite tall and will easily yield planks 20 ft or more. With long straight trunks and no low limbs  they are a bit unusual for black walnut, and are going to have good usable clear grain wood. The biggest problem I will have will be getting them on the trailer to haul to where we are going to mill them.

I hadn't thought about how much the cedar absorbs the epoxy. I had considered milling the strips to 1/8 in. And I expect to have to do a little steam bending or heat bending on some of them. Since I haven't worked with epoxy and fiberglass, I am planning to build some smaller outdoor projects and glassing them to learn what I can before taking on covering a kayak.

I'm sure I will have more questions before I start on it. And I will most likely be buying a book or three between now and then to help me learn as much as much as I can.

Again, thanks for the responses. Any input I can get is very important and valuable to me. 

Dan Thaler

Fri, 07/27/2018 - 06:02

Interesting discussion... I'm just now deciding on what wood to use for my latest build, a microBootlegger Sport. I have a slab of Black Walnut that came from a tree that fell during Hurricane Sandy and was milled and kiln dried. It's a heavy sucker so I don't want too much of it but I may add some accents here and there.

Dan

sbaxter

Fri, 07/27/2018 - 09:10

In reply to by Dan Thaler

Dan it is great for accents that compliment the lines of the boat.  The keel line and sheer lines are great places to accent  and also places that are more likely to take a hit so having a denser wood in those areas is both functional as well as aesthetically appealing.

 

george jung

Fri, 08/03/2018 - 23:26

I'm trying to remember the forum member who used to talk about how little epoxy he used - squeegeed ever bit off that 'wasn't necessary' - and had boats that came in quite light, but still strong.  I can't see an entire boat of walnut being a good choice - beautiful table, really heavy to carry.  And 1/8" strips likely is too thin.  I don't recall who did the studies, but that thin, you're not going to have a particularly strong boat. 3/16 is pretty common, though.  

The trick is making a high performance boat, and not necessarily a display piece - though they're not mutually exclusive.  Good luck - and post pictures!