sceptre structural problems

[docspaff]

Sceptre the Americas Cup boat has problems with buckling of one of the main steel frames cause by the mast being move back 3ft 30 years agriginally the loads from the mast were taken up by 2 strengthen frames either side of the mast.With the mast being move back the load now falls on one of the frames.To add to the problems at this point the beam shelf has decayed and been replaced by a short steel plate.What is the solution to our problem?Is it to strengthen the frame taking the load?Move the mast back to the original position?Or if youre not sure as we are is there anyone you could recommend to advise us[the boat is in NW England at the moment]?

 

[savageseadog]

where are you

 

[docspaff]

preston lancashire

 

[Peterduck]

I'll have to make a few assumptions here; if the beam shelf is decayed, that means that it is timber, which suggests that the whole hull is probably timber, perhaps cold-moulded over steel frames? Clearly, the buckled frame will have to be removed and straightened. how it was fitted to the keel and the beamshelf will determine how it is to be removed, and whether the deck will have to come off in order to remove it. This will probably have to be done to repair the beamshelf anyway. These 12 metres are built with no strength reserve to keep them as light as possible. Witness the one of ours that folded in half at Los Angeles and left the crew swimming. It's all very well to have light boat, but you do have to finish the course to get a place! I would look first at lengthening the mast step to cover as many frames as possible. I can't tell you how long to make tha mast-step, but I would think that 10ft would not be excessive. This should be deep rather than wide, with its maximum depth under the mast, and tapering off fore and aft. The fact that the mast was moved shows that its original position was wrong, so don't put it back there. Then rig tension struts, rods or cables between the mast step and the clamp and beamshelf, so that the struts and deck form an inverted triangle. This is where a sound clamp/beamshelf comes into its own. This will spread the mast load over the whole hull, including the deck, so the deck beams must also be sound. Beefing them up either side of the mast would not go amiss, either. The struts should be rigged for most of the length of the mast-step.
Peter.

 

[Mirelle]

Whoa there. Peter!

"Sceptre" is quite unlike the recent 12 metres!

Designed by David Boyd, whom some would say was the last of the great Scottish keelboat designers in the line of Watson and Fife, very beautifuly built in "semi- composite" construction, with carvel planking over part steel frames and wooden centreline and longitudinals, the whole thing being of course to Lloyds + 100 A1 R Yacht Rules.

I remember having a good look over her when she was in the shed at the Berthon in 1974, before the conversion was done. I doubt if I have ever seen a better built boat.

I would have said that, as designed, her construction was very well engineered indeed, and suited for a very long life. Indeed, she was criticised for being overbuilt at the time. It's what has gone on since that's the trouble!

She was modified for cruising, I think with the idea of being used as a charter boat.

(Edited, because the Forum computer thought I was being rude when I used the correct technical term for Sceptre's construction!)

 

[Mirelle]

Recommendation

She is one of the loveliest boats ever built, and I envy you!

Clearly, the poor old thing has been butchered and needs a proper sorting out!

On the basis of my knowledge of the work that he has done for a friend, who undertook a masive rebuild project, and what I have seen of his work, rather than as a client (I could not afford to be one!) I would certainly recommend that you contact Ed Burnett at Burnett Yacht Design.

The website ought to be here!

 

[Boatmik]

Re: Recommendation

I think you do need professional help to provide an overview of what you have to do.

It sounds like the bent frame may be only part of the problem.

It probably would be possible to get a bolt on reinforcement for the frame fabricated and heavily galvanised. Or add a new frame or two nearby.

Or jack the frame back into position and fit a bulkhead or part bulkhead in plywood to the existing frame.

Quite a few options. But get some advice. And if you don't have the money to get her into good sailing condition now, make sure that the chosen solution won't cause problems when you do have the money to do more.

This is where professional help is useful.

Best REgards
Michael Storer

 

[Boatmik]

Re: Whoa there. Peter!

[ QUOTE ]
"Sceptre" is quite unlike the recent 12 metres!

Designed by David Boyd,

snip

(Edited, because the Forum computer thought I was being rude when I used the correct technical term for Sceptre's construction!)

[/ QUOTE ]

Hi,

I am dying to know what term you used! Can you retype it with some asterisks inserted within the word (keep all the letters intact though). The forum computer won't recognise it then.

This will be educational both from a boat point of view and also for understanding the forum computer!!!

Thanks
Michael