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Kung Faux

Hull/Deck join - Melges 24

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Hi all, 

Having an issue with the external hull/deck joint seal of our 10yr melges 24...looks like a combo of flexing and shrinkage over time has caused the sealant to crack/fall out in high load sections all round the boat ...i plan to dremel out the old material etc..but my question is whether this a job for thickened epoxy, 3M 5200 or something else?

Sorry my phone pics won't load for some reason but I hope you can understand what I'm talking about

Cheers KF

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A hull deck joint is exactly the kind of situation that 5200 was developed for. Flexible and permanent adhesive/sealant.

A relatively inflexible adhesive like epoxy would not be my choice for a seam like that.

I understand many new boats are simply bonded there - no fasteners. What do they use? There are so many magically strong new plastics that it's near impossible to even stay informed about them.

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I haven't found anything conclusive online but my uneducated guess is that it's an inboard or inward flange construction...(but I have read they use a 'proprietary adheasive' to join the two halves with no fasteners etc.)

I chipped away a small section of the cracked exterior sealant to expose the join and from what i can tell the adheasive looks ok, hard as a rock..i just need something appropriate to seal her back up..

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I did this on my Pearson 28-2 (obviously not constructed like a Melges 24).  On my boat the sealant was dry and getting brittle and water could find it's way in.  I removed the mechanical fasteners, cleaned out the joint as well as I could, and put it back together with 5200.  I was careful to leave bolts inserted where I wasn't working so that the hull and deck couldn't get out of alignment.

My boat had an outward flange design which made it easy to do the job solo:

1017009_10151566803220780_695934518_n-L.

I don't like using 5200 in most applications, but think that this is a good one for it.

My Express 37 has a fully bonded hull/deck joint (along with mechanical fasteners).  The documentation says "This allows it to have an inward turning hul and flange that is over 3" wide.  The surface is rough sanded and then permanently bonded to the deck with an enormously strong, catalyzed rigid adhesive.  Then it is bolted together with massive bolts through it's aluminum toerail."

That sounds sort of like 5200, except that 5200 is more flexible.  I can say that the hull/deck joint of the Express 37 is rock solid and I don't think it's ever going to leak.  The 3" overlap certainly helps compare to maybe 1.5" on my Pearson.

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Plexus or g flex.

I have a melges 30 and the decks were not seal to gether they were set in epoxy and then wraped inside and out with glass.

Call melges and ask them for the drawings for the deck joint.

I had to call the designer in California to get the laminate layup drawing for my boat.

I am going threw this same thing as we speak its were the aft spin block are on my boat.

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