Monday, January 30, 2012

Good news and not such good news...

Great evening at the pool yesterday with the Cetus MV. Rolled, re entry rolls and even cowboy stuff went very well. There is a little mystery going on.

I had had a small rim leak in the front hatch which I repaired with 5200. It still leaked, so the folks at Rutabaga helped me put on a pressure cover. We cranked in the pressure until we blew a hole in the 5200 seal. Okay, I thought, when it warms up a bit I can reseal it. Haven't done that yet, yet the hatch has been bone dry after two sessions of rolling like mad. There is now, however, water getting into the day hatch and the small 4th hatch on the deck in spite of the covers being on tight. I have poured water on the rims and cannot find the "leak".

Maybe I need a bigger boat.

Paddle safe...


Buncher said...

I'm NOT varnishing the decks!

gnarlydog said...

Silbs, leaking hatches can be a real mystery, at least to me.
I only had a few kayaks that have been bone dry.
What hatches do you have on the Cetus MV? Kajak Sport dual density?
Well, my findings are that they are suspect. And coincidentally I have just posted an article about leaking hatches:

Brian Day said...

Weird. Hatches are such a pain. If it isn't one thing it is another. Sometimes we think it is the rim and then it turns out that the leak is between rim and cover. Other times we seal the rim and everything checks out right and then the darned thing starts to leak all over again later on.

I think if you generate enough vacuum, you will suck water into the boat past even the slightest imperfection in the seal. Sometimes this happens between rim and deck, sometimes between rim and cover. Could be a poor sealant job between rim and deck, or a mis-shapen hatch ring that doesn't seal properly, or a mis-shapen cover.

Gnarlydog's video about his leaking hatch is pretty interesting. Water is definitely passing between the hatch rim and cover.

Gnarlydog has had trouble with the new style, clip-on Kayaksport covers and I have heard this concern from other folks, too. Are the clip-on Kayaksport covers worse than the standard rubber covers? In general, I don't think so. They seal up tight when everything is working right. It may just be that there is less margin for error with the snap-on covers since there is less surface contact between the rim and cover. They may accentuate any imperfections in the rim or cover.

As for your mystery, I'm not at all surprised that you can't get water to leak past the rims when you test them. I bet we are looking at a pressure differential caused by temperature when you take the boat from a cold environment into the pool. Air heating in the compartments of the boat would press outward on the covers and slowly escape, allowing water to enter as it does.

Why is the front hatch dry now? Maybe you got it sealed just exactly right this time, and maybe the other covers were put on in such a way that some slight imperfection in the hatch or rim was allowing water to pass.

I would try poking or slicing a hole through the pressure relief valves in your bulkheads to make sure they are venting properly. Sometimes they aren't sliced in production. A scalpel or xacto knife is a perfect way to make a tiny (say 1/4 inch) slice in the vent.

I'll be curious to see if that has any kind of impact on pressure in the compartments and leakage at the pool.

Silbs said...

Thanks guys. I am going to follow up on your recommendations. Just on the lake where water temp is near freezing and air 54F. The front hatch was sucked down when the boat hit the water suggesting the valve isn't equalizing the pressure.

Silbs said...

...and Buncher: I just might get a teak kayak...NOT!

Steadfast Ahoy! said...

New/bigger boat? hopefully not that rust bucket you pictured, That one's scary. Come to Atlantis (my latest post) to see nice, "bigger" boats.

Silbs said...

Got it! I once had a 42 foot sailboat (cutter). More work than I wanted.