4 metre creek crawler

Yes, if I was going to be paddling in the same conditions I'd make sure I was kitted up too. Mad if you don't. Sheltered waters in the sub-tropics are a bit different though.

 

Warm water.... ummmm. Not where I live unfortunately. Have fun.

 

That's the plan. I think I'll start working out the patterns, etc since the consensus seems to be that the basic design is sound.

 

Keep listening to those voices, they'll keep you alive!

 

Thanks for directing me to your thread - I hadn't seen it before. Looks like a nice boat.
My initial impression, just glancing at the deadrise, is that it might not be quite as stable as many recreational kayaks of that size. My Wee Lassie looks similar, and it is not nearly as stable as my Chuckanut 10, of similar beam.

Spray skirts, for a rec kayak, keep out water that drips off your paddle and onto your lap - which can be a considerable amount, over time, and very annoying. The skirt need not be whitewater quality.
Good drip rings on the paddle help, too.

You talked about heat shrink Dacron, as they use with aircraft. It's pretty dainty stuff, IMO. I find you can heat shrink the 8oz polyester I get from George Dyson very well, and it is not dainty at all.
Rub strips of HDPE, or hardwood, are easy to apply. You can also just add an extra layer of fabric to the keel line - I often just "glue" it on with whatever I'm coating the skin with.
In any case, I don't recommend sliding down a concrete boat ramp to launch any SOF boat!

I like your bulkhead idea. Do a search on the qajaqusa.org forum for some SOF examples. Float bags are good, but it's still impressive how much water a bulkheadless kayak can take on.

Clearly, you don't need to worry about hypothermia - I think it's giant crocs, great whites, box jellyfish, blue-ringed octopi, or the occasional brown snake or death adder hiding in your cockpit that you should be prepared for. Good luck!

DG

www.GentryCustomBoats.com

Coincidentally, here's a pic, just posted on another forum, of what I was most worried about in Oz . . . .

 

Sure, but this has around 30% more length than a Wee Lassie which means a corresponding increase in the distance from CB to metacentre. That translates into a substantial increase in GM. The Wee Lassie also lacks the roll damping you get from chines. This thing wont be as stable as a Chuckanut 12 but should be better than a Lassie.

I'll use what I can get locally. The aircraft stuff is 3.7 oz is easily available. Two layers of that should be good enough. That's the recommendation for the Platt Monfort boats.

Been there already. Google FTW.

The implementation shown there is a bit messy IMO, although probably the only way of doing it with a traditional Greenlander. What I was thinking of was just a basic plywood bulkhead with a wide enough edging and the skin glued to it. It works in flexible plywood boats. I can't see why it wouldn't work with SOF. It's just another flexible skin glued to a bulkhead. Hey ho. Something like Sikaflex would probably be good for the adhesive. There may be a slight ridge across the bottom at the bulkheads when under hydrostatic pressure, but I can't see that causing any more drag than the chines really.

 

Just for interest I ran a basic initial stability comparison between the 4 metre (13'1" wl) creek crawler and a 3 metre (9'10" wl) boat that uses the same sections, with the height of the DWL being adjusted to keep the displacement constant. The idea here is that the shorter one should give a basis for estimating relative stability compared to a Wee Lassie or Chuckanut 10.

If the sections of the 4mCC are much the same as a Wee Lassie then, as shown in the attached image, it could be expected that the 4 metre boat would have around 25% more initial stability.

I've also included (in orange) the outline of the master section for a Chuckanut 10, as taken from Dave's offsets, with the immersed area being the same as the other design. There's not actually a lot in it when comparing the shapes. The beam of the C10 is almost identical. The flatter floor of the C10 would give a bit more form stability at low angles of heel.

I can't be bothered calculating how much the difference is as Delftship Free does not do inclined hydrostatics and doing them manually is a PITA. However, I doubt it would amount to more than 25% or so. On that basis I would expect the 4mCC to have much the same stability characteristics as a Chuckanut 10, which should be fine.