Port chainplate/settee strength

Please see the post RE new 7.9 masts

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dave
Posts: 727
Joined: Fri Jan 02, 2004 10:39 pm
Location: Little Rock

Port chainplate/settee strength

Post by dave »

Hey folks, Dave here. Been a while since I posted.

I'm just finishing up on a mast step rebuild and lifeline stanchion/rotten balsa repair on another 7.9. Found something that made me a little nervous while doing the repair, and I wanted to give y'all a heads up. The GOOD and very rare news about this issue is that the fix is easy, quick and cheap! When's the last time that those three words came together concerning boat repair? :D

The port Chainplate comes through the deck and bolts into the forward, vertical face of the settee, in front of the sink. While peeling the carpet off the roof and DB trunk to start cutting for the mast step repair, I cast a gaze at that front side of the settee and noticed that the carpet on the port side ran down onto the V berth (meaning it was taped to the hull), but NOT up the up the forward edge of the settee. This REALLY made me stop and think a second, so I peeled the carpet up from the V berth/hull joint and also from the hull where it meets the settee. The fiberglass tape on the former ended before it even got to the settee, and even in low light without my readers I could see that the tape joint was partial lifted away from the hull from the aft edge of the tape, forward about a foot!!! :shock:

This is NOT a good situation! I couldn't believe that the forward side of the settee wasn't glassed to the hull to help distribute the rigging load, so I pulled the sink to check the inside. There was some tape running up the interior settee/hull joint but again, it stopped about a foot from the top and ALSO showed signs of lifting away from the hull!!! :oops:

The repair and strengthening was easy as stated. I ground the gelcoat off the forward side of the settee from the hull inward about 3", then did a grind on the facing hull surfaces and the existing tape, then also did the same thing on the needed areas inside. I then blew all surfaces off, wiped down with lacquer thinner and applied two layers of 20 ounce biaxil tape with epoxy resin to all. Problem solved and only took about 1.5 hours and very little materials.

I don't know if there is any settee that's ever pulled away from the hull on a 7.9 but then again, the multiple weaknesses in the design and/or build of the mast step area gives under load, acting as a partial strain relief for the chainplates. Believe me when I tell you that the rebuilt mast step in this boat does NOT give one fraction of a millimeter, so the chainplate mounting areas are going to stressed even more than before! Also and as always, I'm not running down the boat! It's a great boat overall, but all boats have problem areas.

One might be tempted to say that I should have ground the old lifted tape areas off and re-glassed those, but I think not. The lifting wasn't from tape edge to tape edge, only about .75" up the hull edge. The whole hull/settee unit is way stronger than new without the added cost of grinding off and replacing these tapes, so it's a win from a work and ultimate cost standpoint.

Pull your carpet up in these areas and pull the sink (two screws). Just may save you some big trouble and BIG bills down the pike.

One final thought: A good friend and long time boat repair/composite friend of mine was once sailing on a Shock 35 down at Key West Race Week. He said it was fairly typical for there; fairly windy and lots of waves and chop. While beating to windward, the rig came crashing down.......... AFTER the now detached settee ripped a settee sized hole in the deck and launched the unfortunate rail rider into space!!!!! :shock:
AJ Oliver
Posts: 188
Joined: Sun Jul 27, 2003 8:59 am

Re: Port chainplate/settee strength

Post by AJ Oliver »

Hey Dave -
Thanks I will check that - and the starboard side as well where some boats have had issues with the chain plate & bulkhead interface.
dave
Posts: 727
Joined: Fri Jan 02, 2004 10:39 pm
Location: Little Rock

Re: Port chainplate/settee strength

Post by dave »

No problem AJ, I like to help out if and when I can.

Still need to over drill and fill the chainplates on this boat too, but that has to wait a little longer. No matter the type of boat: if the chainplates go through balsa core, they need to be removed, any bad balsa reamed out (hopefully that's ALL it needs), the hole over drilled and allowed to dry for a while, then taped from the bottom and filled with epoxy/high density filler, then re drilled.

This still won't be a 100% cure for water getting through the chainplate because any movement at all will slowly break the caulk seal, but at least no water will ever again be able to get into the balsa from this area. Many folks make the mistake of putting new caulk on top of old silicone. Bad idea: nothing sticks to silicone rubber after it's cured, even new silicone! :oops: For any caulk to bond to any surface, that surface or surfaces must be 100% free of any old caulking, all dust and moisture gone and then wiped down to remove any possible body oil, etc. I prefer MEK for this, it kicks acetone's butt when it comes to cleaning, degreasing and dewaxing! That's why many high $$$ paints suggest using MEK on aluminum as a paint prep, not acetone. :wink:
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