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Hull and deck

Posted: Fri Apr 10, 2015 6:12 pm
by jimandpat
Hi forum members. I need help please. We bought a Merlin October last year. Just noticed a dimple in both sides of the hull. Looks like the shrouds have been over tightened and distorted the hull where the chain plates are bonded inside. Will need to reinforce the hull inside and hope the dimples will come out again. Advice please. Jim :evil: :!:

Re: Hull and deck

Posted: Sat Apr 11, 2015 3:50 pm
by rhumlady
Is it still the same with the tension released?

Re: Hull and deck

Posted: Sat Apr 11, 2015 4:03 pm
by Eeyore
I was speaking to the Selden agents down in our yard last week about rig tension. They basically said its impossible to overtighten a rig as the bottlescrews are not capable of doing damage. On our Tempest the chainplates are in the middle of the side decks attached to bonded transverse plywood webs which are very strong.
How are the Merlin ones attached?

Re: Hull and deck

Posted: Sun Apr 12, 2015 8:03 am
by jimandpat
To Derek and Eeyore. Thank you for your reply. I to have heard its hard to over-tighten the rig. On Goldie the cap and lower shrouds fix to a single deck fitting close to the cabin side. This is transferred inside by a steel bar to a fixing on the hull. The hull fixing is a piece of 1/2 in ply bonded edge on to the hull below a shelf approx. 2ft above the seat moulding and is approx. 12in long 6in wide at the top and 4in wide at the bottom finishing 12in above the seat. Outside you can see a slight vertical line were the inside mounting is and below this is a dimple where the hull has been flexed in. This is not great but very obvious with the sun on it and is on both sides. I have slackened the rig to see what happens butt the hull fixing looks too small to spread the load and I intend to re-do this to spread the load over a larger area in width and depth and hope I can remove the outside marks. Boatyard said they have seen this before on Merlins which is why I asked the question . Many thanks. Jim

Re: Hull and deck

Posted: Sun Apr 12, 2015 1:45 pm
by rhumlady
I previously owned a fractional rig Dufour 1800 and as it was my first boat I asked questions about rig tension. The answer I got was you can't tighten a fractional rig properly unless you are on the wind with the Lee shrouds loose. I didn't get around to doing that I must admit but the boat went on to win quite a bit of silverware with someone who did. Not knowing the Merlin but from your description of the chain plates I guess she is fractional rig with the caps and lowers brought aft and swept back spreaders. If this is correct then there is going to be a lot of tension there.

Re: Hull and deck

Posted: Mon Apr 13, 2015 8:20 am
by jimandpat
Good morning Derek. Yes you are right Goldie is fractional rig with swept back spreaders. As the shrouds both go to the one chain plate I think this should be very substantial. On boats with more than one chain plate the load is spread to a larger area rather than just the one. Goldie was fitted with a new in-mast reefing mast and rigging 4 years ago and is well raked back. I'm not sure if this is right but will have to see how the sail sets before doing anything about it :?: I'm not very good with computing or I could send pictures which would make it clearer. jim

Re: Hull and deck

Posted: Mon Apr 13, 2015 5:56 pm
by rhumlady
Big problem with fractional rig is the increased tension in the standing rigging. I was told it had to be kept tight or there was a risk to the mast. His then feeds back into the chainplates causing the likes of your problem if they are not substantial enough. The Konsort has the same bar below for the lowers but I don't like it much and am toying with the idea if a wire stay with a turnbuckle belowdeck and using that to remove the loading at the deck at least. Also looking at changing the chainplates at the deck as i don't like the 'A' bracket arrangement. I would prepare something that lines up with direction the stays take to the mast. Maybe beefing up the hull around the fitting that the bar goes to would be a good move.

Re: Hull and deck

Posted: Mon Apr 13, 2015 8:25 pm
by jimandpat
Hi Derek I think the deck fitting would have been beter nearer the toe rail instead of the coach roof it would have given a more upright pull in line with the riging rather than pulling the hull fitting inwards away from the hull.But I've have to work with what I have and will beef up the existing till I'm happy with it and hope to get rid of the distortion in the hull.Good night :)