Hull deformation

I posted this earlier in the H16 forum but thought I would get a wider audience here. The links below show images of a bulge in my starboard hull on the outboard side in the area where the pylon shoe is located. A forum member suggested I read up on a Hotline article on pylon shoe hull repair, which I did, but my boat has none of the symptoms described in that article nor is an outboard hull bulge a symptom of that particular failure. The pylon does not seem to have broken free of the shoe nor does the shoe seem to have broken free of the hull. My deck is not soft and my tramp frame is not loose. I hear an occasional clonking sound in my hulls but I believe that may be flotation blocks shifting around.

http://picasaweb.google.com/lh/photo/18 ... directlink
http://picasaweb.google.com/lh/photo/YD ... directlink

My primary objective of this post is to determine if:

1. Anyone has ever experienced a hull condition like mine?
2. If not, if anyone has ever even seen a condition like this?
3. If not, is this completely unique to my boat?

If the answer to 1 or 2 is yes and I have some latent manufacturing defect that will cause a catastrophic hull blowout three or four miles offshore I think I need to be concerned. If it is completely unique to my boat I have my own theory as to what caused it.

It's a fairly common condition on older boats.

It is certainly related to the pylon shoe, and as recommended in the other thread, a port behind the pylon is in order to see what's going on.

There's obviously been downward pressure exerted on the pylon shoe. Whether it occurred at the time of manufacture (when the deck and hull were assembled - someone may have botched the pylon length measurement and they "made it fit" when the hull/deck were clamped together) or afterwards, only inspection will tell.

There is nothing noticeably or obviously loose and I've been sailing with it this way since I've owned the boat (4 seasons). Have you ever seen a pylon shoe just punch its way out of a hull? Most of the time I don't even notice this unless the sun hits it just right. The previous owner took the boat apart and left the hulls stored flat on their outboard sides for over ten years. I wonder if it was just gravity that caused the walls to deform there or if something was lying on top of the flat hull adding pressure at that point. I'm a staunch believer in the old axiom if it works...don't fix it. Maybe I'll make this a winter project.

If there's no obvious sign of the pylon shoe being loose (grinding noises, depressed area around the deck fairing, etc.) then you're probably OK. I'd still cut a port in over the winter to take a look at it.

As you can see from the photo, the pylon shoe lands on an area of foam core. It takes some significant downward force to "telegraph" that bulge through to the outside.

Like I said, I suspect there was a problem in original assembly. The decks and hulls are molded separately, with the pylons molded into the deck in an inverted position. Adhesive is applied to the deck and wet fiberglass cloth is draped over the pylon shoes. The deck is then turned right side up (still in the mold) and clamped on the to hull (still in the mold). If the pylon is a bit too long, the shoe is going to exert some outward pressure on the hull - eventually resulting in a bulge like you have. The bulge may not show up for years.

What is that plate made of? The flat thing just above the foam looking shoe piece at the bottom. That's not metal is it? A metal plate pushing against my hull would scare me.

On really old boats, the "plate" was a piece of resin-soaked cardboard. In any event, it is not metal. Newer (80's) boats don't have the "plate".

Hello
Have you measured how much of the pylon tube is protruding above the hull, compared to the other side or another Hobie?

From the picture it looks like the closest tube is sunk lower in the hull than the one far away (even with perspective distortion, it should be opposite)

_________________
Poul
FxOne 165

I'd Rather Regret The Things I Did, Than The Things I Didn't

I think you are seeing an optical illusion created by the way my righting line is draped around the pylon.

Are you still sailing in Denmark this time of year or is your season over? Do you use a drysuit there?

Did you measure it ?

We have a late summer this year. Last weekend, air was 20 centigrade and water 15, so it was shorty weather but of course I had to repair a small damage to a hull.
Coming week will be from 15 to 10C so I might get my drysuit out. Its still quite warm, as long as you don't get to much spray, high speed and waves really cools you down.

Contenders for olympics and other racers, will be training all year round, except when the water is stiff

In winter you do need a follow boat as it would be dangerous to lie too long in the water when its around 4C

_________________
Poul
FxOne 165

I'd Rather Regret The Things I Did, Than The Things I Didn't