4 metre creek crawler

This is just something I knocked up as light relief after getting far too serious with analysing fast rowboats. I'd appreciate feedback from people who know more about kayaks than I do.

There's some nice places around here where I wont be able to fit a long rowboat with ten foot oars, and those skin on frame boats sure are quick and easy to build as well as being light and good looking. Maybe having two boats wouldn't be so terrible.

I like the look of the Mill Creek 13 and Dave's Chuckanuts so thought I'd have a crack at something similar. The numbers seem ok. Stability is in the range that Nick Schade regards as "suitable for beginner paddlers". Now tell me where I've screwed up.

Dimensions are:

LOA 4.00 metres (13' 1.5")
DWL much the same obviously
BMax 0.685 m (27")
BWL 0.612 m (24")
Draft 0.085 m (3.3") @ 90kg (200lbs) displacement.
Depth 0.213 m (8.4") baseline to lowest point of sheer.

 

I've never seen a kit or plans that were similar, but I have an Emotion Edge that's only 9'6" with a 27" beam but a 350 lbs capacity. What I love about it is that I can get into almost anywhere and it's super maneuverable for getting pictures. I went paddling in one of the sloughs of the Snohomish river yesterday and was able to paddle up the little tiny creeks that I could never think of getting into in a bigger boat. She's surprisingly fast for her size and tracks very well. I spend a lot of my paddling time looking for and photographing derelicts and abandoned things and I find the Edge is absolutely perfect for what I do.

I guess the only point I'm trying to make is that you can actually go smaller than 4 Meters and get an even handier boat for what you're describing.

http://www.emotionkayaks.com/HTML/Kayaks/Edge.htm#

 

Just an alternative.

Loa 3,65 m
Boa 0,76 m
Disp 0,105 m^2


js

 

Yup, could do. I'm a bit wary of going too small though. 4 metres is still very moderate in size IMO and I'd like some speed in reserve. It doesn't take much current to bog down a really short boat.

HJS: I can't see any advantage in that catamaran thing. I don't need the extra stability. It's got to be heavier and have more wetted surface. It's more difficult to build. It's also uglier.

I suppose what I really want to know is if what I've drawn will balance nicely. It has to track well and not weathercock. It also has to turn when required but I don't really need it to spin on a sixpence.

 

From the aesthetic point of view, the software seems to always generate the middle panel with the same width, which I don't much care for. Overall, seems like a nice design. Small, light boats like this will weathercock depending on the balance of the weight. If you keep the fore and aft sections immersed evenly, it should do OK, but may need a bit of experimenting.

 

Not sure what you mean about the middle panel. I chose all the control points myself. They weren't generated automatically.

 

The second strake.

 

Oh gotcha. Just seemed to work well that way. It's mostly hidden below the waterline anyway

 

There's nothing wrong with it, just a matter of preference. The shape looks well balanced.

 

It should be fine, if anything it may be too strong tracking but that is very much a matter of personal preference, it should turn well if you edge it a bit.

All sensible sea kayak designs weathercock if the wind gets strong enough which is why many commercial designs have rudders or retractable skegs but I don't think you need to worry below 15 knots and even 20 isn't too bad. If you have the skills a less strongly tracking kayak can be easier to paddle in strong winds because it's easier to correct.

The thing I would look at with your design is the sheer height and width at the front of the cockpit as it looks like it may interfere with paddling. If you lower the sheer in the middle of the boat you will have less risk of bashing your fingers and it will be easier to keep your strokes close to the boat. The steeper pitch this will create in the deck will also make water run off faster.

If you tell me the intended use for the kayak I may have some hints but for a general purpose design it looks good. 4m seemed to be the default length for kayaks about 30 years ago.

I like the rowboat design you posted, when are you planning to build it?

 

The idea is for sheltered waters. Smallish river, side creeks, local dam, etc. TBH I don't have the skills for sea kayaking and have no real inclination to develop them at this stage.

Wind speed sounds ok. The sort of thing I have in mind means when there is a breeze it's usually under 15 and mostly blowing straight up or down the river. I'll take a look at revising the sheer a bit.

Rowboat? Oh, that rowboat. Well, having come up with a shape I like and got my head out of OCD mode (which mode I tend to get into easily) I realised that if I actually want to get out on the water for what's left of summer (or at least before winter) I'd better come up with something that can be built quickly and easily. Ergo little SOF yak. I don't really take kayaks seriously. They're just something to mess around in, so I can just do a good, honest job of one and be satisfied. If I go for a rowboat I'll take it seriously. That's just how my brain works. At this stage that wouldn't be a good thing.

 

Question on building SOF 'yaks...

Do you put some sort of abrasion strip on the keel outside the skin? I got to thinking about this the other day as I was sliding down a concrete boat ramp to launch (the dock was too high). Despite being close to skinning my SOF boat, I'm still not sold on the durability of this construction method, especially when I look at all the scratched on the bottom of my plastic boat..

 

Working in a commercial boatyard, we noticed there was one material that was literally impossible to sand, it was too hard. This is "Interprotect 3000", one component of Interlux's blister control scheme. It's a white epoxy (?) paint that goes on f/g after the blister is taken care of with other parts of the program. When I built a cruising dinghy from ply and epoxy, the bottom got several layers of cloth, then a final finish of two coats of this stuff.
16 years of hard use later, it's scratched and gouged but pretty intact, so could be one very lightweight answer to chafe on a kayak.

 

I know some people use metal or plastic skid strips on the keel. A high density polyethylene would work pretty well I think.

Re durability, I had an idea which I think I might try. Apparently the best covering if you want something that'll end up light and wrinkle free and stay tight is heat shrink dacron, which makes sense. That's why planes use it. It also doesn't require any sewing on a kayak, which is a nice bonus.

Problem is that it's not as durable as ballistic nylon or some other things. Ballistic nylon is a bit difficult to get hold of around here, but what I can get easily is acrylic canvas (the stuff used for sail covers). This is strong but a bit stretchy, very UV resistant (unlike heat shrink dacron) and colour stable in a nice range of colours. So, if I use that up to the chine just above the waterline and then put heat shrink over the whole boat, I should (hopefully) get something which is going to handle the sun hitting the inside of the boat, provide a nice safety margin for inadvertant abuse, and still smooth and tight as a drum outside. Would paint the outside obviously to protect the surface from UV. Inside shouldn't need any painting.

Anyway revised the sheer as per KJL38's recommendation. Stem and stern height are unchanged. Lowest point has dropped a bit over an inch. Minimum freeboard is now 4 inches. Same flare in the sheer panel. BMax reduced by about an inch. I also gave the keel a smidgeon more rocker in the ends of the boat. Good enough?

 

It still looks like a double paddle will touch the gunwale every stroke. The hydrodynamic shape is cool and the tumble home sternpost will reduce windage while extending the w/l like an Adirondack boat. Nice.