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Old 14-04-2008, 21:50   #16
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Dear Wheels

The only concern I see with this is on the loading on your stays
the change in angle that all the stays go to means that the displacement of the horizontal load is going to require a much great force be placed on the new stays
I could calculate some indicative changes in your loading, but the larger mast would have had a larger footprint on all of the stays to transfer the load
This may definitely mean larger chainplates and fixings, but also heavier stays
The rest should not make too much difference. The extra weight at the top for the leverage it creates will reduce the level wind you can sail in to the same extent as the weight, but otherwise would mostly be similar.

I am a novice on the details on the sails and what their behaviour would be with this change, but the forces in those stays will increase dramatically

Cheers
Greg
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Old 14-04-2008, 22:16   #17
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If you supply me your I, J, P &E and boom height above Datum. (Specify what the datum is) and boom height above datum, max beam, displacement, ballast chain plate width and distance aft of the center line of the mast I will engineer out a solution to your wire size that you can then relate to your chain plates.
Shroud angles may become an issue. I take it that you chain plate width is close to an Élan 43 and is the aft sweep?
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Old 14-04-2008, 22:27   #18
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It's too much - without doing any calcs. I'd cut off some top and bottom and re-attach headbox to top. If you're not reefing till 20 knots you're a bit underpowered but the extra 10' is too much. I'm a N.A. by the way.
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Old 15-04-2008, 00:56   #19
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Hi Alan.

You’ve posed an interesting question, insofar as the proposed increase in mast height of 10 feet (over three meters) represents roughly a 20% increase. I’m no expert, but would suggest you get in touch with the original designer and get their opinion on this from them in writing. I would assume that the original choice of mast already reflects an optimum balance for your vessel.

Depending on the insurance policy you have for your boat, I would also check with the insurance company, whether this modification of the specs alters the risk substantially and if they are willing to cover it, insofar as the entire boat could be subject to far higher stresses than it was built for, in unfavorable circumstances.

Perhaps these considerations are too conservative but I would remain on the safe side and carefully assess all the aspects before going ahead.
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Old 15-04-2008, 01:59   #20
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Weld up holes, relocate spreaders...

Is it possible to weld up the existing spreader/mounting holes (perhaps with backing plates) and then relocate all fittings into their correct positions.

It may be possible to do this with backing plates under the weld so that the mast is not unduly weakened.

As the main stresses may be where the spreaders are mounted this may not weaken the mast greatly.
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Old 15-04-2008, 04:12   #21
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if you can take the mast section dimensions you can probably get all the mast details out of the selden catalogue (they list both their current and dicsontinued lines). there is a lot of info in the catalogue

Seldén Mast AB
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Old 15-04-2008, 16:42   #22
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Is it possible to weld up the existing spreader/mounting holes (perhaps with backing plates) and then relocate all fittings into their correct positions.

It may be possible to do this with backing plates under the weld so that the mast is not unduly weakened.

As the main stresses may be where the spreaders are mounted this may not weaken the mast greatly.
Don't weld your mast anywhere below the hound! All you have done is weaken the mast by welding. All fittings fitted to a mast below the hound should be drilled and tapped or riveted.
The only welding anyone should do is the tapper if required and usually this is above the hound.
Cheers
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Old 16-04-2008, 02:22   #23
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...The only welding anyone should do is the tapper if required and usually this is above the hound.
Cheers
What's a "tapper"?
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Old 16-04-2008, 04:56   #24
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What's a "tapper"?
Had me puzzled for a while but I'm betting on "taper" - the tapered top section of the mast above the top spreaders.

Do I get a prize ?

John
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Old 16-04-2008, 12:51   #25
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Aloha Fard,
Thanks for mentioning welding on a mast. I don't think its a good idea to get a torch near an aluminum extrusion. I've had it done on my mast and would never ever do it again. I'm worried about it constantly
Kind Regards,
JohnL
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Old 16-04-2008, 14:24   #26
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Thanks guys. Lots to think about. Maybe some more info will help.
Firstly the boat is 45ft and weighs in at 26Ton. As steady as a Rock...(well she is FC :-) It does not heel over much under full rig and starts to get a little loose in 25kts, so hence the first reef at 20kts.
The mast is just the extrusion. Pre-punshed for all of Seldons components and Anodised. So I realy don't want to do any welding.
The Mast is deck stepped but making it through hul;l would not be possible. All the line exits and winch mount points would be too low anyway.
We have to find spreaders, but do have most of the fittings as second hand items. It does mean we have to go to SST wire.
There is no rigging yet. I was hopping to stick to Galv, but the unavailability of fittings is not goign to allow us to use Galv. The reason for second hand is the NZ Seldon supplier won't support us using their gear because the Mast is second hand and they can not gaurantee it. Even though it is a Seldon dealer that is doing the rigging for it. The mast had slight damage. A small indentation. I pushed this out with a clamp arrangement I made. The mast was originaly off An Elan 43 and was replaced with a new one by the Distributor. The insurance company sold this one as a usable spar, yet if there was an issue, you would have though the Agent would not have allowed the insurance company to sell it on. Oh well. So even though an expert has looked at it and said it is OK and he is one of their dealers, They still will not support us. So we have found bits and pieces to do the job anyway.
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Old 16-04-2008, 14:36   #27
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What happened to the old rigging? was it reused on the new (replacement) rig, or just the spreaders were used. If not maybe it is sitting in the riggers surplus bits and pieces in Auckland. Probably wouldnt be too hard to find out who did the job.
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Old 16-04-2008, 15:10   #28
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If you don't have the rigging, spreaders, etc. you might be best to put it on e-bay and begin your search over again. Sometimes chalking things up to experience early in the game is the best route. From experience. And you did have an interesting experience motoring over to get it!
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Old 16-04-2008, 17:24   #29
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What's a "tapper"?
So shoot me!
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Old 16-04-2008, 17:46   #30
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Thanks guys. Lots to think about. Maybe some more info will help.
Firstly the boat is 45ft and weighs in at 26Ton. As steady as a Rock...(well she is FC :-) It does not heel over much under full rig and starts to get a little loose in 25kts, so hence the first reef at 20kts.
The mast is just the extrusion. Pre-punshed for all of Seldons components and Anodised. So I realy don't want to do any welding.
The Mast is deck stepped but making it through hul;l would not be possible. All the line exits and winch mount points would be too low anyway.
We have to find spreaders, but do have most of the fittings as second hand items. It does mean we have to go to SST wire.
There is no rigging yet. I was hopping to stick to Galv, but the unavailability of fittings is not goign to allow us to use Galv. The reason for second hand is the NZ Seldon supplier won't support us using their gear because the Mast is second hand and they can not gaurantee it. Even though it is a Seldon dealer that is doing the rigging for it. The mast had slight damage. A small indentation. I pushed this out with a clamp arrangement I made. The mast was originaly off An Elan 43 and was replaced with a new one by the Distributor. The insurance company sold this one as a usable spar, yet if there was an issue, you would have though the Agent would not have allowed the insurance company to sell it on. Oh well. So even though an expert has looked at it and said it is OK and he is one of their dealers, They still will not support us. So we have found bits and pieces to do the job anyway.
Alan due to the displacement of your yacht compared to the Elan 43 I very much doubt that the mast you have will be strong enough.
In fact I know it will not be strong enough.
You need to compare the RM for the two boats.
You have stated that your boat "is as steady as a rock" The displacement of an Elan 43 is around 8500kg depending on the model of the boat. Your boat weighs 26 ton.
For your own safety please get your boat engineered out and then compare the moments required in the mast to the second hand one you have.
Go to a good mast maker that has inhouse engineering or supply me the info requested in my earlier post. And I will do it for free for you.
PM me the details if you want.
Good luck
Fard
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