26M Daggerboard

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duncan.cairney
duncan.cairney's picture
Hi Roly, the dagger board

Hi Roly, the dagger board mould is in my garage. Let me know if you want it shipped to you or if you would like me to drop it off at the fabricators in Glasgow (Paisley). I am not sure what the position is with the fabricator given the current pandemic but I can check if you wish.

kind regards

Duncan

Duncan

simon.armitage
As you may know, Mike Clarke

As you may know, Mike Clarke made the mould using my old, slightly damaged dagger board and then made his own board; he posted instructions on this site. One of the things he discovered was that the board appeared to have a built-in weakness so that it would break on significant contact but would not damage the inboard housing. I pass this on so that you may discuss this with your fabricators.

I think this is one of the most useful assets owned by the association as it is particular to the M model and I thank Mike again for donating it to us.

Look after it, fellow members, keep it safe and if it moves around the country could the new carer post a note so we know where it is.

As for non-members, maybe the treasurer and secretary have an opinion. I think it should only be available to members only and it is not going to break the bank to join in order to get access to it.

Thanks a lot, keep well and safe and hoping to get a sail in later this year.

Simon Armitage

Commodore

Sowenna 26M

keith.barton
Hi All

Hi All

Please also remember, I have the Macgregor Rudder 19 mould stored. I would like to pass out on as we have very little space but as we are still stuck in Scotland can’t do anything yet.

Keith

Star 26M

roly.simpson
I quite agree that the mould

I quite agree that the mould should be considered property of MOA UK (Thanks mikes donation) and should Only be accessible to members.

I'd have to find out cost if transportation but I would suggest for the moment that if Duncan is happy to store it then it remains there and we ask the local fabricator to make further boaeds as requested since he has already made at least one to good satisfaction.

Since mikes mould and technique followed exactly that of the original I think the inherent weakness is catered for.

I plan to contact the fabricator directly. However I'm not sure how difficult it will be for Duncan to deliver it.

It would be good to know whether there are others interested.

Roly

duncan.cairney
duncan.cairney's picture
It is no problem for me to

It is no problem for me to drop it into the fabricator as I live only half an hour away. I certainly insider the mould to be the property of the club and for now I have no problem storing it. The board is stored in a strong plywood case kindly manufactured by John Pompeii and the case is suitable for shipping if required. Should anyone wish to have a board made here by Martin McGrath in Paisley my preference is that they make their arrangements directly with him and just lets me know when the mould should be delivered and collected again. Please feel free to call me if you want to discuss, my contact is at the start of the post along with that of the fabricator. Kind regards to all. Duncan

Duncan

simon.armitage
I have emailed Macgregor and

I have emailed Macgregor and BWY to enquire if there is a built-in weakness in the dagger board and will let you know when I hear back, not that I doubt Mike, but my old board might just have been damaged. It does make a lot of sense to have a weakness which could save a lot of work on the interior casing.

Simon.

mike.clarke
For clarity,

For clarity,

There is not a weakness built in as such it is just that the design is such that when the dagger board is in the lowest position the parts in contact with the dagger board case are weaker than the dagger board case itself. This means that if you hit something its the dagger board that breaks and so reduces the risk of serious damage to the hull which would probably sink you. I have read reports of people doing daft things like making steel dagger boards or strengthening the dagger board that would inevitably cause catastrophic damage to the hull if they hit something when its down. Its very important that the mode of failure is to loose the dagger board and not the boat. My original comment on the failure mode was due to the design of the internal stiffener in the board being in the centre of the core rather than strength at the edges where it would do more damage and the fact that its a hollow tube of fibre glass which fails in a way that is unlikely to do a lot of damage to the casing. It also allows for a partial failure without total loss of function BUT - once the central core of the board is damaged either by pulling away form the sides or a structural crack the board is unusable and not repairable if you want to retain the rigidity and safety for future use. I would strongly advise against any repair to a damaged board other then minor cosmetic repairs to the leading and trailing edges or the bottom. The bottom of the board is a solid lump of resin some 50mm thick which can take a bit of a beating and be repaired but once the sides or the core is cracked the stiffness is lost and will not be made good by a repair or patch. If you have even a relatively small crack on the sides of the board make sure you inspect the interior as it may well be that the core is damaged and once that happens the dagger board will fail under stress - almost certainly at the most inopportune moment in a heavy sea! The hardest part of fabricating the board is making sure that this central box section is bonded properly to both sides of the board when the two halves are being assembled. I used an endoscope to examine the bonding inside the board once the resin had cured. I also found that the original board I took the mold casting from had some damage to the core that was not evident from the outside.

Hope this helps.

Mike C - Tarka 26M

mike.clarke
PS don't be too surprised if

PS don't be too surprised if Macgregor or BWY are not too keen to discuss the design of the boards as its their product and I suspect they are not going to be thrilled by us making our own boards instead of buying theirs!

simon.armitage
 

From BWY

Yes. Not so much a specific weak spot, just the boat is a LOT stronger than the board. In addition to the thick hull bottom, the 300# of fixed ballast is molded around the lower end of the daggerboard trunk making it very substantial.

Thanks,
Todd

MacGregor Parts & Accessories
Blue Water Yachts
7116 220TH ST SW, UNIT 15, MOUNTLAKE TERRACE, WA 98043
206-282-4261, line 3
www.shop.bwyachts.com

I am much relieved.

Simon

roly.simpson
Great , well done Simon for

Great , well done Simon for taking that initiative to contact BWY....sounds a helpful chap.

Roly

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