More than one way to skin a cat

[anewhouse]

It was a bit of a toss up whether this post rightfully belonged here or in the Kayak Foundry forum.

After building four strip built kayaks, two of which were designed with KF, I decided to try something a bit different. I thought I couldn't get more different than a SOF designed with KF.

I wanted something very similar to my KF designed stripper. The main differences were that I made it 5.5 metres instead of 5 metres and reduced the width from 56 cm to 51 cm. I also made the chines harder to accommodate the way the frame would shape the skin.

In theory that dropped the stability from 92 to 66. I was quite happy with that prospect because I thought the lower seating position would reduce the difference, because I only intended to use it on lakes and estuaries and also because I have happily paddled kayaks that were much less stable than my stripper.

One of the reasons I wanted to try a SOF was that it would be quicker. I was also prepared to experiment a bit. Some people might read that last sentence as, "I was prepared to ignore some of the good advice available from the experts".

Some of my decisions were influenced by materials and tools I had available, some because I thought they were a good idea and some because I just wanted to try them.

I used Tom Yost style plywood forms, but used 9mm ply instead of the usual 12mm. I finished up not using the very small form at the stern.

I used Paulownia for the stringers because it is about 10 to 20% lighter than WRC and seemed to be good to use on two of my strippers. When I was dressing the timber, it cleaned up at 22mm instead of the usual 19mm. As I hate turning good timber into sawdust or shavings, I used it at that size.

My original idea was to steam the sheer strips to reproduce the exact shape of my stripper, but changed my mind and let the timber dictate some of the shape. That added a bit of extra time as I had to check and recheck that my cutouts for stringers were in the right place and at the right angle.

I was also paranoid about the water pressure changing the shape of the skin from my carefully designed shape, so I added a couple more stringers to the hull. I also wanted plenty of room for my feet and knees, hence the extra stringers on the deck.

I decided to skin it with clear PVC for the novelty value and on the assumption that this would be a temporary measure as it is not as durable as other skins. There seem to be two readily available thicknesses of clear PVC. I think I made a mistake in choosing the lighter one.

I couldn't find an equivalent to HH-66 in Australia and couldn't be bothered buying a stapler, so I attached the hull half of the skin to the top and inside of the sheer strip with a contact cement that starts white and dries clear. The problem with doing that instead of using staples is that you only get one chance to get it right.

I used the same contact cement to glue the deck to the hull Tom Yost style, but I didn't quite trust it to hold, hence the duct tape around the sheer and on the stems.. I know it spoils the look of it , but I have since learned that clear duct tape exists. I might try it later.

I decided to find out how good thickened epoxy is as a glue. That is all that holds it together.

I have finished it and I have paddled it, so here is my assessment of what I always saw partly as an experiment.

The good:
It is pretty light at 10kg. If I had not been so carried away with using so many extra stringers I could have easily saved another kg.
It is much more stable than I expected.
It has a turning circle similar to a supertanker, but otherwise handles well.
It took about 50 to 55 hours compared to the 200 I spent on each stripper.
The skin on the hull is a good fit.

The bad:
When everything was removed from the jig I had to align things to build the kayak, some of the rocker at the bow was lost. As I didn't have much there in the first place, it now has almost none. I can live with it as it is, but will modify it when I reskin it in a month or two or a year or however long the clear PVC holds up.
I may try a heavier PVC on the hull. I think I got carried away with trying to save weight.


The ugly:
The complex shape of the deck around the cockpit meant that I wasn't able to get a smooth fit. It keeps the water out, but it looks a bit rough.
The silver duct tape looks out of place.

I might be exceeding the size of allowed attachments, so I will add the last couple of photos to the next post.

[anewhouse]

The completed kayak.

[Braithwaite78]

Nice! Way to think outside the box, man If your strippers werent getting you enough attention out and about, this should do it

How does it handle the drive to the water on top of your car?

[anewhouse]

I have only driven a total of about 50 km so far with it on the roof rack and there doesn't seem to be a problem.

My only concession has been to use flat webbing straps instead of the ropes that I have been using successfully for the last 35 years to keep the kayaks on the car.

If it is like the strippers, the problem is not so much the drive to the water, but the time it takes as you are unloading and loading to answer the questions of curious onlookers. Nick Schade calls it "Parking Lot Syndrome". I think he suggested that if you are in a hurry, you just tell them the stripper isn't made of wood, it's just stick-on vinyl.

[jimbo]

first let me say: sweet!

i noticed the loose pvc around the cockpit and it got me thinking...i used to build radio controlled model airplanes when i was younger, and we would make a balsa frame and coat it in this stuff that shrinks when heat is applied...i wonder if that would work on an SOF 'yak? as i recall the brand name was mono-coat, and it was a heavy duty mylar i think...i made for a nice tight skin on wings and such...

ok...so a quick search found their site, http://www.monokote.com/ but i wonder...how thick should the skin to be? i have been thinking of building one myself.

[anewhouse]

This description on their site makes it sound good.

MonoKote's superior shrink and adhesion make it the easiest plastic covering to apply. And once applied, its special adhesive gets a grip that not even years of accumulated exhaust residue can break. MonoKote is also one of the most puncture- and scratch-resistant films on the market- qualities you'll find in all of the rich, vibrant colors available. Given that it's priced comparably to coverings that offer less, it doesn't make sense to use anything other than MonoKote. For low-heat applications, try Top Flite EconoKote®, available in 6 foot rolls of 9 different colors.

However, I suspect that while it might be a reasonable price to cover a model aircraft, the cost might be prohibitive for something the size of a kayak.

I like the sound of, "one of the most puncture and scratch resistant films on the market."

[jimbo]

yeah...i didn't think about the price...my dad was always paying for it back in my model airplane days. i just remember how well it would shrink to give a nice tight skin. i saw 6 foot rolls, and it didnt register that it would be 6 feet LONG not 6 feet WIDE.

[Jimyak]

this guy uses mono coat http://gaboats.com/

[Kudzu]

How did I miss this thread?? Way Kewl boat!

I am toying with a sheathing one in clear plastic too. I bought some last night for flotation bags and was surprised at the price. Cheap enough!

[anewhouse]

On the car and on the water.

After about 6 hours on the water in the last week, including 3 hours today with a few friends, I have learned a few more things.

It is quite fast and it seems that while it might cruise at a similar speed to my stripper, the difference is that in this one I can accelerate a bit more before extra effort becomes a waste of energy.

I definitely should have chosen a thicker clear PVC. I would like to stick with the clear skin for a while longer, even though I will probably eventually use that vinyl that Tom Yost uses. So I might have another go with heavier clear PVC. maybe when the weight of my patches exceeds the extra weight of a heavier skin.