Do I need to worry about this?

I have a bulge in my starboard hull below the pylon. I've had it since I've owned the boat and sailed with it for four seasons. I used to hear an odd bonking sound in that area which had no rhythm or cadence but has since stopped. Now I'm worried. Am I getting ready for a blowout.

http://picasaweb.google.com/lh/photo/HL ... directlink

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

In a word - Yes.

There was a fairly recent hotline article about repairing broken pylon shoes. I would look it up, 'cause that's almost certainly what's going on with your boat.

sm

Okay, found it. Sept '09 issue. Curiously outboard hull bulge is not indicated as a symptom in the article. Nor are any of the symptoms quoted found on my boat - inboard vertical gel coat cracks, grinding noises, pylon fairing depression, excessive tramp frame movement. I have none of these. The repair procedure seems fairly complex but leans towards lapping additional glass cloth onto the pylon shoe which I doubt would improve or affect the bulge I see in my hull. Before I bought my boat, the hulls were stored for ten years lying flat on their outboard sides. The bulge could just be some weird force of gravity that pushed the pylon shoe down or something. Maybe I'll just roll the dice and try to stay out of heavy seas.

Almost certainly something is going on with the bottom of the pylon connection. If it were me, I would install a port hole BEHIND the pylon in order to inspect what's going on. There's really no harm in doing this. You'll need hull access in order to do the repair, and without being able to see the inside of the hull, the best you can do is speculate.

Portholes also have the benefit of providing improved hull ventillation and storage - just don't put the port in front of the pylon.

sm

Why is it not a good idea in front of the pylon?

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Marc...
1978 Hobie 16 Keoke, sail# 36 84

There is a lot of load on the hulls in front of the crossbar due to the inward & upward load on the bridle wires. Think about how hard you pull on the mainsheet and then multiply that force by the 6 or 7 to 1 mainsheet system. The bow tangs see all this load, and the deck carries a portion of this load. When you cut a port hole in front of the pylon, you're basically cutting out a significant amount of load-bearing structure and replacing it with a thin plastic plate.

A lot of people put port holes in this location, and they're probably OK, but putting the port behind the pylon is a much better idea.

sm

Thanks for the explanation. Makes sense now.

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Marc...
1978 Hobie 16 Keoke, sail# 36 84

Well the main reason I posted this is to determine if anyone else has ever experienced a similar problem or if it is completely unique to my boat. Think I'll move to a larger forum.

Sunvista: My first thought was a loose shoe, too, but I've never seen symptoms exactly like yours, so you may be right that it was caused by storage. If you can flip the boat over or suspend it somehow, you should be able to see movement if the shoe is loose. It may take a lot of force to simulate real live loads, and you'll need to be careful not to confuse it with any pylon to casting looseness. Unless there's an obvious problem, I'd sail the heck out of it and watch for a worsening condition.

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Jerome Vaughan
Hobie 16

I am absolutely astounded by this. It's hard to believe that fiberglass could deform that much and not crack or shatter. Amazing!

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1990 "Formula 1" H16 (# 009)

Bulges and cracks at the bottom of the hull in this area are an indication that there is an issue with the pylon "shoe". It is not unique to your boat.

Again, I would put in an inspection port and inspect - it is the only way you will know for sure what exacly is going on. But it is almost certain that a repair is necessary.

sm