The death of the deck joint?

[deckhand]

I was at the sailboat show in Annapolis MD this past weekend and among other things noticed that there wasn't a single boat in production that had a visible or even hidden deck joint! Now we're talking everything from Bene's and Catalinas to Morris' and new Tartans. They were all glass together and faired perfectly smooth. Could this end the long battle of "recaulk your deck joint, it needs to flex" vs. "no way, go solid, it'll never leak and be stronger"

my only problem with their methods is that a lot of these builders didn't put any rub rails in ... That could get ugly fast.

pictures on my site.

http://dkyrejko.com/hobyn/?p=60

[suntreader]

When I think of all the trouble deck joints cause, glassing them in seems like a no brainer. There is probably still a place for bolted joints in day sailors because of the labor involved with glassing the joint and the smaller boats having lower forces involved. On my project boat there is only one bad joint leak through some cap rail bolts, if the joint had not been heavily glassed at the factory I shudder to think of the problems that could have happened.

Dave

[Bluenose]

I think that this will be my last foray into the deck joint conversation. This will be quite a rant I am afraid so feel free to page down.

*** Begin Rant ***

The End of the Deck Joint

I really think that the title of this post would be more descriptive if it was "The End of the Bolted Deck Joint". Because I think that boat builders are still laying up the hull separately from the deck and then joining them after they have installed the interior. So we have change from a secondary bolted deck joint to a secondary bonded deck joint. This joint can easily be made to be strong enough to take the loads. But consider this. In order for the maximum loads in the hull or deck to be transfer across the joint the glass joint must me be at least as thick and strong as the weakest part (either the deck or hull). So this means the area along the top of the hull that is twice the thickness of the area just below it. Fairing this "perfectly smooth" will be a challenge. I freely admit that I am a skeptic from years of being beat on as structural Engineer always being asked (told) to let things go. But wrapping a couple of plies of glass around the deck joint doesn't cut it. A real structural fiberglass deck joint would require a change in the original hull mold to allow for the tapering off of the thickness of the deck joint glass. Perfectly faired and joined composite parts either require highly precise molds (not usually common in boat building) or filler. This is a quick sketch of what I would like to see.



As you can see both the hull and deck require an indentation of their molds to allow for the hull to deck joint splice. In two dimensions this looks pretty easy but in three dimensions it gets tricky fast.

And I also wonder what requirements boat builders designing their boat to and are they actually telling that to the public. Are they building their boats for sheltered coastal cruising but then showing pictures of their boats in South Pacific lagoons? I think that the prime focus for boat builder is money, which I can understand. But money and safety rarely live together in the same neighborhood. There are probably only a handful of really critical joints on a boat so if a boat builder wants to speak of safety, why not show some sketches of their boat building techniques.

I have on multiple occasions while working for major Aerospace companies been asked to either sign blank drawings or sign drawings with little or no structural analysis. On one of these occasions I pretty much started boxing up my belonging before the money people stopped pushing. This from an industry with lots of regulations and oversight. My only point in mentioning this it say that we as boat owners are the only ones responsible for the safety of our boat. The fact the most or all boat builders do something wouldn't count for much in my book.

*** End Rant ***

my only problem with their methods is that a lot of these builders didn't put any rub rails in ... That could get ugly fast.

I agree completely with the comment. My favorite deck joint has always been an inward turned flange with the deck bolts going through aluminum toe rail.

[deckhand]

I forgot the camera today so I didn't take any images. Heres a diagram to illustrate.