Basic questions from a would-be beginning boat builder

This is a continuation of a thread started in the Hydrodynamics and Aerodynamics sub-forum:
How much less efficient would a planing hull sea kayak be? https://www.boatdesign.net/threads/how-much-less-efficient-would-a-planing-hull-sea-kayak-be.64175
I've probably given up on the idea presented there of a "planing hull" sea kayak.

I want to make my own skin-on-frame kayak, so I'm changing sub-forums.

I am trying to find basic info here. I have very little knowledge of carpentry and tool use, and no space for a band saw.

The Yostwerks website assumes a lot of wood working/carpentry/marine lingo knowledge. I need something more basic. How basic is "Building the Greenland Kayak, A Manual for Its Construction and Use", by Christopher Cunningham? Is there something even more basic?

I would probably be launching and testing in waves a few feet high.

How thick would the pallet wrap need it to be? If food wrap is about 35-40 gauge, is 350-400 gauge (possibly composed of more than one layer of pallet wrap) about right?

I'm not worried about traditional design. Could I hold the stringers together for a quick trial with duct tape?

And does this sound like a good plan, to experiment with length, shape, and width, without cutting new wood for every trial?:

1. Start with stringers that are a little longer than is probably needed. There needs to be a little rocker (longwise curvature) at the ends, so the ends of the stringers are out of the water, to reduce the leakage where the stringers poke through the wrap. Once the proper lengths are determined, make a final cut.

2. Start with solid cross frame pieces, except for the hole needed for my feet. Cut holes in the center when the design is finished.

 

Mitch,
I grew up around boat builders. Lived with my family on a plywood on wood frame schooner, I went to trade school almost 40 years ago for furniture making and design. I have been in the carpentry and cabinet making trade ever since. I have not, however ever built a boat, though I have been drawing and drafting my concepts for the day I hope to build one for myself.

Please believe me when I reassure you that the skills needed for what you are planning, are not complicated. Get a basic book on woodworking and learn some of the language. Learn the language to a new discipline and you are half way to mastery.

I'm sorry I can't be of more help with some of your questions about PVC, etc. I simply don't know, but the wood part will be simple and straight forward.

You want to approach wood with a clear plan, be patient, sharpen and tune your tools correctly and accurately. Follow your pre-laid plan systematically. Practice on scrap pieces. Have a clear solid work station and a high quality square and a good measuring tool that you can trust. Double check your mark with the plans and measure again. Use a jig or a guide whenever possible.

Select straight, clear wood with no knots or angled grain. If you need strips of wood cut, get someone with experience and the right tools (usually a common table saw) to do it for you and cut extra pieces.

A basic hand saw will suffice to cut to length at any angle. A well tuned hand plane, not a belt sander, to shape glue joints such as scarfs (two pieces of wood glued together by planing a long taper in them)

A coping saw would be enough for the odd cut that isn't straight, but a decent jigsaw will make the work go faster and more accurately.

Epoxy glue is best, but Titebond III is great and easy to use.

Dry clamp first, make sure everything works smoothly, then take it apart, apply the glue and clamp it all back together again. Don't be in a hurry.

Remember, even if there isn't enough time to get it right the first time, there's always time to do it over.

Good luck and it will be fun following along.

-Will (Dragonfly)

 

I would use shrink wrap instead of pallet wrap. It is a lot tougher and much easier to get a good tight skin.

 

Two of the most important tools are time and patience.

However, if the plan is still to experiment with the hydrodynamics, they may not be compatible with building repeated iterations quickly.

I'd also question whether SOF is the right way forward for what you want to achieve. The hull shapes possible are limited by the curves that the stringers will allow, whether they are wood or some other material. These might not align with the hydrodynamic hull forms needed.

How about a cheap, basic second hand kayak and gluing on slabs of foam to try out different hydrodynamics quickly and relatively easily?

Once you've got the hull shape that works for what you want, then you take the time to build it beautifully.

 

Check this out. It has most of the traditional kayak designs. However, kayaks are specialized for each use. For example, a kayak for hunting whales in the open ocean will be different from one for fishing in shallow water. They were all made to fit the user too.
https://www.amazon.com/Bark-Canoes-Boats-North-America/dp/1628737921

 

People said SOF's are the easiest to make yourself. Also, I like the light weight. Though if I paddled in waters with a lot of big marine predators, I might want something sturdier.

Nick Schade's page (httpwww.guillemot-kayaks.com/sea-kayak-recreational-kayak/petrel-play-petrel/longer-really-faster?fbclid=IwAR2_2IYYTFuNvpSi4p0I4QVclTaaorowdczF8Mofk10dj9B9-S4hBY4UJtg) gives optimal waterline size estimations to minimize paddling effort, including:

3 mph: 18.9" x 8'
4 mph: 16.8" x 10'
5 mph: 14"" x 13'
6 mph: 12.2" x 16.1'
7 mph: 11.1" x 17.7'

(He didn't list all his estimation parameters. I wonder what paddler weight and sea conditions he picked.)

Typical sea kayak club paddling rates are 3 or 4 knots (3.45-4.6 mph); perhaps going up to 5 knots (5.75 mph) against a strong current. Maybe boaters stronger than me might go 6 knots for a short burst to catch a wave. The 4 or 5 mph sizes seem a good compromise.

None of the appropriate off-the-shelf boats are light enough for me to easily carry. More to the point, they are too wide to keep up with the people I like to paddle with, so adding foam won't help - I would need to raise my center of gravity so much it would mess up my testing. So nothing like I need is available cheap.

The only exceptions are flat or open water race boats; but at the speeds the people I paddle with go, they are too wide and too long. And they aren't cheap.

The fast racing kayaks and surf skis I've tried (with approximately cylindrical hulls; though I only tried them for a few minutes) were too unstable for me. Plus even used race boats are expensive, except the old 4 meter slalom boats, which wouldn't make very good open water boats for a number of reasons. (I tried, some time ago.)

While I've never been an expert paddler, I've had a number of kayaks over the years. I currently own:

1. An old model Current Designs Caribou (S??), 42 lbs, 21-3/4" x 17'6". At my weight (about 150 pounds) the waterline is about 13'6" - 14'6"; the bow bounces a lot paddling into 2-3' chop, which means I have to work very hard to keep up, and couldn't do so all day long.

2. A skin-on-frame boat designed and built by someone else, which takes less effort to paddle. 30 pounds, 19" x 19'. At my weight the waterline length is about 11'-12'. The weight is fine. It handles well in waves. The waterline length is about right by Nick's numbers. But, it is probably somewhat too wide; The cockpit is too low to the waterline, so I cannot re-enter it from above at sea without swamping it; the deck is too low for me to lean forwards. (I have poor flexibility, and need to bend my knees more to do that.). I can do a re-enter and roll, but the small round cockpit only has a rope rim: not ideal for holding a neoprene spray skirt. It is hard to get into, and I can't put the nylon spray skirt the designer made on while underwater before running out of breath, so I get a lot of water inside.

3. A Wavesport EZ-Go 50. I could not possibly keep up with sea kayakers, or re-enter it at sea without help.

I was reasonably happy briefly trying someone's 16"x16' SOF, but it isn't for sale.

I've looked for a good book or class on hand tools for a long time. Everything I've found uses big power tools.

I also looked for appropriate classes, like the wood shop classes high schools used to offer. I can't find anything like that. I spent a few weeks of the "Apprentice for a day" classes at Chesapeake Bay Maritime Museum. But that only covered a few small areas - mostly planing. They aren't running classes mid-pandemic. And I need more general knowledge.

Anyway, anyone have opinions of the woodworking knowledge assumed by Cunningham's book?

 

Seems like you are married to your idea and won't listen to anything that doesn't agree with it. Go for it. The plan will either succeed or fail.

 

Roy Underhill's 'The Woodwright Series'

Tage Frid


-Will (Dragonfly)

 

I built 8 Yostwerks sof kayaks.
You don't need power tools for anything but cutting the basic frame strips.
Get someone to do it for you - cabinet shop?
Scarfs are difficult but can be done by hand. Practice a lot and try to break each one until you get them good.
Use polyester skin. Not shrink wrap. It won't last long and it will distort in the water, ruining your "hydrodynamic" testing.

How narrow do you want to have the boat? If you can't push a 19" boat fast enough you need to exercise more.

The construction with absolute freedom to change geometry is strip planking. Not as cheap as SOF and not very easy to quickly change shape, unless you make a small boat and add foam to expand the lines.

IMHO

 

Depends how many layers you build.
Pallet wrap sticks to itself well.
I've actually done it Gonzo, have you?
I couldn't stick my thumb through it.
It works well for sea trialing hull designs.

 

I've used different materials, including tarps and poly sheeting. Shrink wrap is really tough and doesn't need a perfect fit. It tightens up with heat and the wrinkles dissapear.

 

I'm not trying to learn hydrodynamics - I'm in my 60's and that is something people get PhD's in. This isn't just about the boat. It's more about how my body interacts with the boat.

I'm not a beginner to kayaking. I've been paddling since the early 1980's, beginning with whitewater, which I did a few hours a day after work for many years, and more recently mostly switched to tidal rivers and some open water. I've owned about 10 kayaks over the years, have tried many others, that other paddlers brought to rivers, club sessions and trips, and that people like Chesapeake Lightcraft brought to club sessions. I'm certainly not an expert paddler - though I've taken lessons from a few. I know the way my body interacts with my kayaks, and have ideas about what needs to change about that, to make me better able to keep up with sea kayak paddling clubs, based on trouble I've had doing so with the boats I have tried. I also know how the boats I've owned interact with waves and winds. I've also seen some of the problems other paddlers have had - e.g., skegs and rudders are constantly breaking and needing service. Also, since I've never owned a boat with a skeg or rudder, that simply isn't the way I learned to turn.

I've been shown, and have verified, that I can paddle much more efficiently if my paddle stays almost vertical in the water, starting far foward, next to the boat, and exiting the water fairly far behind. But my shoulders are much narrower than most people my weight. So to do that well I need a thin boat - say 16" or less next to my body - much thinner than anything commercial out there except certain race boats.I could glue foam to such a boat to try out boat shapes. A thin boat is also much easier to roll. But even used race boats of those types are very expensive.

I've been shown that one can paddle much more efficiently if one lean forwards. Also, that helps a lot with rolls, as does being able to lean strongly sideways - neither of which I've been able to do in any boat I've owned. (There was a time, when I paddled on a daily basis, that I could hand roll whitewater and my sea kayaks. My technique was and is absolutely awful, but I had strengthened the muscles that control the hip and knee enough make it work anyway. I'm weaker now. I have failed to roll some of the wider consumer market boats, even with extended blade paddles.) Because I have short hip flexor muscles, I can only lean forwards if my knees are fairly deeply bent. I can't do that in any off the shelf boat, except sit-on-tops - and very wide boats where my knees splay to the sides - but as I said, wide boats won't do for me to keep up with paddling clubs.

Some racing surf skis are thin eough to be good starting points. I could maybe glue foam to them. But they are quite expensive too - and they are used very differently from ordinary kayaks. I need something I can tuck my knees under to roll.

Also - they are mostly fiberglass or other composites. Is it easy to glue to those things, and then get them off again?

It possible, because of the flexibility thing, that I would be better off with a boat I could kneel in, like some canoes. I honestly don't know if I could be comfortable paddling like that all day. I should try it. I might even consider a surf ski.

Would a very thin stitch and glue boat that I built be a better starting point? I suppose it would be easier to glue foam to it, especially if I didn't paint the wood. None of the available kits are thin enough for me. Some people claim stitch and glue boats are relatively easy to make - though maybe that is when you start with a kit that has pre-cut wood? Would it be easy to make such a boat sufficiently leakproof if I had to cut the wood with hand tools and a jig saw? Is there a practical way to fill the gaps temporally, but still provide a surface I could glue stuff too? I wonder if I sealed the gaps with duct tape, whether I could find a glue to attach foam pieces.

I only have space for, budget for, and have only been shown how to use a few tools:
1. At the museum-taught sessions, I used a plane a fair bit, and somewhat less, a "draw knife", and a Japanese style double edged pull saw. I've bought such tools. I also used a plane at a club-taught session to make a Greenland paddle (a long stick with flattened ends) from a board - not precision work.
2. I've sharpened a pocket knife, a dive knife (carried while whitewater boating), and ice skates, using hand tools. I was sort of shown how to sharpen a plane on a bench grinder. I tried to sharpen a straight razor, but can't get it sharp enough to do a good job. I've no no experience sharpening anything else.
3. I've tried to use a hammer, but have trouble nailing straight. I definitely can't do what the electrician showed me, where he drove nails in on a double bounce, one quick tap to set the position, and a stronger one to drive it in.
4. I've some experience with screws and screwdrivers, but have trouble creating holes at right angles to he surface. (I bought a center punch and a "drill guide" to try to make clean "guide holes" for mounting figure skate blades, but haven't used them much yet. The experts I've watched work on skates don't need such aids.)
5. In connection with sharpening ice skates, I've have and have used calipers and a micrometer, though not high end ones, and I have trouble getting consistent results - anyway, I doubt a kayak require that level of precision. I have tape measures and dollar store rulers.
6. I have an electrician's pliers (with wire cutter and stripper sections), a wrench set, and a square, but am not expert in their use. I own an electric drill and a jig saw, but don't know what I'm doing with them. I managed, twice, to break dollar store hacksaws. I used a tap and die set just barely enough to extract a screw whose head had stripped. I have a small vise.
7. I managed, very inefficiently, to cut and glue foam pieces to outfit kayaks, for a tighter fit.

These do not constitute a solid foundation and background for using tools and woodworking techniques. Just a random selection of mostly self-taught skills, often poorly done.

BTW, I wasn't aware there were people I could go to, to cut wood strips to function as stringers. That's an interesting idea.

I get that skin-on-frames are difficult to experiment with on shape, because you build the shape into the pieces you cut. That is why I asked:

In other words, I wanted to gradually cut down the pieces until I got a shape that works well for me. Now that I think of it, I could use duct tape to temporarily seal the leakage where the stringers poke through the wrap on the early generation tries, when I don't know yet how long I'll need the stringers to be.

I'm thinking the PVC tarp idea may be a good idea for a skin that is durable enough to be reused. I don't know if it is durable enough to be used in the long term, and it can't stretch or shrink to shape.

Perhaps I should build a small scale model, that I couldn't use, just to get experience using tools and techniques without wasting a lot of material. Or instead make a short fat boat that was useless to me, but which would let me test out whether I can make something float without wasting much material, and how thick the bow support arch needs to be to be strong enough to empty out someone else's boat with a few hundred pounds of water across my bow, and how strong the back deck needs to be for re-entries.

 

Skin on frame might be what you need.
My Yost boats were first assembled by driving decking screws thru the long frame strips into the bulkheads.
This sets the shape and allows me to take a strip loose to make adjustments to the joint.
Yost bulkhead shapes and the cutouts for the longitudinal strips are not all that precise in my experience.
For my boats, I pull off two opposing longitudinals and reattach using filled epoxy, inserting the wood screw to hold the joint until it hardens.

The deck screws are capable of holding the shape without epoxy, at least for a time.
It might work well with the pallet wrap idea that others use (I haven't tried it, hence my unproven dislike)
You could take such a frame apart in order to shim out the attachment of the longitudinals, in order to get a modified shape.
It probably is even possible to add a small piece of plywood on the face of a bulkhead using deck screws, so that you could make multiple changes at a given location.

The only issue I would have is the possibility of the extremely sharp wood screws protruding thru a bulkhead. The plywood is relatively thin and you need to drive the screw completely thru to hold well.
You could cut some foam and stick it over the end of the screw.
Remember that all of this is to just make a temporary trial, not a lifetime boat.

When you finish developing the shape that you want, take it apart, cut new bulkheads to match your last shape. Reassemble. I personally would use epoxy to set the joints, but more typical lashing would do.

Note that I personally do not cut the notches shown by Yost in the frames. Initial location by screws and finished epoxy fillets make it un-necessary. But, you could put in the notches if you wish.
Again, I have found that the location and shapes of the notches shown by Yost rarely fit well, especially with the lower two stringers.

One suggestion: use the Yost suggestion for bulkhead thickness. I tried thinner and it broke. Don't use Fir marine plywood. It splinters in the narrow sections shown on the bulkhead, then you end up with one thickness of wood. Not enough

PS: Your last message finally has all the information about your capability and needs. We often see this during the statement of the problem. Some of us make poor assumptions and therefore poor suggestions.

Marc

 

mitchgrunes:
You answer your own question by the last post. It shows that a kayak that works really well for you would have to be custom made. That is the opposite to production boats, which are a compromise that is not ideal for anyone.

 

That seems to go against that curious theory which says that a designer can only be a good designer if he has sailed a lot and is a good sailor. Because only then he can design a good boat. But of course, it will be a good boat for the designer and it does not have to be for the rest of the world. I'm talking, as you can easily deduce, from serial ship production which, apparently, is what this thread is about. All designers, in that niche market, design what they believe, based on their experience, which is the best, thinking that what they like is going to satisfy the vast majority of the public.
That, together with a good decorator that makes the floating artifact very beautiful, can give rise to what is considered a "good design" (it would also be necessary to define what that is for each one, but it would be the story of never ending)