Boat Building Forum

Find advice on all aspects of building your own kayak, canoe or any lightweight boats

Test idea and Re: I liked your response
By:Mark Bodnar
Date: 8/11/1998, 9:53 pm

George catches a lot of flak for his opinions - some fair some not so. While at times his responses are rather caustic and suggest that the rest of us little people will sink in our boats when we come across poor conditions, the intent and content of his responses (if you ignore the tone) contain some good information.

This list is intended to share ideas to improve all our building skills - George has some valid ideas to add to that. Let's be realistic - all of us building boats would prefer to shave off 5 lbs, especially if it could be done without weakening the boat. The question is what are the tradeoffs (and there are aways tradeoffs). Can an beginner do a proper glass layup? -Not if you listen to George - so here's the tradeoff - I'm not going to get as good a glass job/paint/hull lines/strength as a pro BUT I get to build it! If it costs me a few extra pounds or a slightly weaker hull I'll live with it.

If George (or anyone else) has suggestions that I can use to build a better boat - let me know. But if it's so difficult that I can't build the boat or it adds significant time/$ - I may not use the idea.

It seems to me that if the kayaks we are all building are as inherently risky a George suggests this list should be losing members. I for one plan to drive a 1/2hr next weekend for my first salt water launch - I'll be in the Atlantic Ocean off a rock/sand beach (likely in 3-4' waves) - if you stop hearing from me I'd suggest you all start listening to Georges advice!

As for the current argument about the better boat - I can't imagine what route you would paddle to completely destroy a boat - and as Nick suggested, because the event is so infrequent it becomes random. (I even have a friend that built a Cape Charles last year with NO outer or inner glass - only taped seams and painted hull - he paddled all last year on rocky and rough lakes and has no holes to show for it)

I think the test panel idea holds the most merit. Make 4 - 1'x6' strip built panels - (cut and you have 1'x1' panels for testing). 1 panel - Nick's method 1 George's 1 extra glass with thin wood 1 thin glass N wood (maybe even throw in a 4mm plywood panel)

Now you have 6 sections from each to test (weight of each one should give a good idea of epoxy/wood/cloth concentration - only epoxy can't be pre weighed). Best test would seem to be puncture resistance (torsion would not be as significant an effect when built into a whole boat). You could even drill a few small holes into some of the panels and submerse them (~12hrs) to evaluate the glue differences. Place panel on a table, supported only around the outside 3". Lower a heavy weight (via rope pully) onto the panel - on the bottom of the weight a 2" dia rounded knob to simulate a typical impact point. If the weight is attached to a scale you could read how much weight is no longer being supported by the rope and therefore must be resting on the panel when it gives out (or even have a tester stand on a scale - they should be proprortionatly lighter according to how much of the weight they are supporting on a pully).

I don't have an engineering background but this seems to me to test all major differences - 1 thickness of glass req'd, 2 glue vs epoxy between strips, 3 safety differences. If you can't pick up variations with this type of simple method it would seem unkikely that they would have any bearing on building and therefore we should just stick with the easy/fast methods.

What it does not test is the most telling - should we care? How many PSI should a hull withstand??? Can someone carve up a fiberglass and a plastic kayak for extra test pieces - that would provide a good gold standard.

At least we would have part of the answer, then we could each make an educated decision about time saved/weight gain vs strength - are the tradeoffs of time and effort worth the effect? - To each his own. I imagine that George will alway strive to make the lightest, strongest kayak on the block - Nick will work to make it easier for others to enjoy building thier own kayaks.


> Sailing is different than kayaking. Here the losing boat is often
> destroyed and the winning boat is not in sale-albe condition. The
> stakes provide reasonable incentive and compensation.

> As I understand most of the posts here over the last year or
> so:

> Using a mathematical model is not acceptable, using test samples
> is not acceptable, and using real boats is not acceptable.

> Please note what I offered Nick: no money or boats change hands,
> I pay my travel expenses, he picks the course, we have a crowd partial
> to him perhaps. Except for pride, its a no lose situation. I got the
> expected response, "its not fair".

> If you can come up with a better (than my challenge) test of
> kayak durability and a reward system that compensates for the risk,
> I will fund it. But lets try to keep the entry cost down. Had I won
> every foot or bicycle race I participated in I would not have paid
> my training expenses I expect that happened in sailing also.


Messages In This Thread

Test idea and Re: I liked your response
Mark Bodnar -- 8/11/1998, 9:53 pm