A New Bigger Mast

[ahun]

After the unfortunate incident of losing the mast, I might be lucky with a find. There is a mast laying around the boatyard and its owner willing to sell it. However, the parameters, not surprisingly aren't identical. So, how far can I go in increasing the height?

Boat: 36' (12 m) full keel, fibreglass, beam 3m

Old mast: 12.8 m tall, the cross cut profile is 200 x 160 mm, one sets of spreaders, they are 1180 mm long measured from the mast

New mast: 14.1 m tall, profile is 240 x 170 mm, two sets of spreaders, the lower and longer is 970 mm measured from the mast.

It's a 10% increase in length, it comes with all the standing rigging (unmeasured yet) that are in good condition, if only for the time until they are replaced for new. It means, no cutting off of mast.

Would you go for it? Any insight or thoughts are appreciated.

Thank you.

[model 10]

Somebody added 5' to the mast on our boat. I often use 1 reef.
How are you going to deal with the second set of wires? That's a big deal.

[ahun]

Good question. The chain plates are attached to a ???? (what's it called, the encapsulated, dedicated attachment place, like a semi-bulkhead) so the idea is to add an extra chain plate to the other side of it. Done.

[model 10]

You know about spreader angle right? If you had to shorten them, it wouldn't be such a big deal.

[ahun]

Well, have to measure and do some triangulation, but I suspect it's not too far. On that note, neither of the masts have aft swept spreaders.

[JC Reefer]

I’d see about shortening it. You can use sta-loc’s and shorten the rigging. If you can get away with only cutting the bottom then it would be easy but I doubt you’ll be so lucky.

Here’s to hoping.

[Fore and Aft]

I would be shortening the mast. The goose neck fitting height from your old mast will determine how much you need to cut of the top and bottom. I would be cutting the mast down since your sails suit the shorter mast. Also that extra weight up that high might affect your stability. Maybe not much, but it’s not that hard to shorten a rig.
Cheers

[ahun]

Thank you all. There will be completely new configuration of the whole canvas area, new sails, furling, everything. Plus, that ugly dog house structure means I have to rise the height of the boom, significantly.

[Tillsbury]

I'd be going for the extra length. You can always reef but it's hard to argue with what would be significantly larger sail area when the wind is light.

[barnakiel]

If you keep the old sails now they will for a bit differently.


And the lower spreaders may be a tad too short. Check chainplates base too. The spreaders need to be in compression or neutral, never in tension.


Overall, when two masts are very similar, this should work.


BTW when two shrouds end up on the same plate, there is a special link plate involved to minimise side pull. Look up Selden catalog for what the idea is.



b.

[ausnp84]

I did just this two years ago - swapped an 11m mast for a 14m one. It was keel stepped and I needed it decl stepped, so I chopped 2m off the bottom, refitted the bottom plate, and that was that! New rig with sta-loks, replacement good condition sails, new wiring, etc.

Had a lot of people getting in a flap about the excess weight at height making the boat unsettled and dangerous... the boat’s now done two Biscay crossings and is currently on it’s way back to the Med!

Good luck and keep us posted.

N

[boatbroke]

Hi Ahun,

The extra wright aloft is something to consider as it will effect you righting moment.

As the boat leans over, imagine a 10kg weight on the end of a 14m lever.

Not saying it will be critical reason to not do it but something to keep in mind, it is not just the power of the sails to consider.

Race boats often will get bigger masts and go to a C6 or PBO (composite) rigging to keep the weight back down.

Conversely just going to a lighter rig (carbon rig/PBO rigging) can be akin to adding many kilos to of lead to a keel but the boat actually get lighter overall!

Just weigh up the costs involved for the whole project. It may be more cost effective to try keep the old fittings and just get a new mast extrusion.

It may also be possible to sleeve the broken section.

The local rigger should have an idea, else where is the boat now?

Good luck mate.

Adam

[CarinaPDX]

A sistership of Carina was built with a 42' mast, a Lefiel meant for Westsail 32s, and I built Carina with a 45' mast as per naval architect's original design for light weather. Because mine was stepped on the house top and the original design was keel-stepped I had to go up a size in cross-section for the lateral support (Carina is narrow). If I had it to do over again I would go with the shorter, lighter mast. Carina is more tender as a result of the extra weight and leverage aloft. Also, a lot of the time I sailed with a reef tucked in - the larger sail and decreased righting moment meant more reefing. Of course the advantage is that she could sail well in lighter winds, and the extra mass kept the boat less responsive to beam seas. If you go with the taller stick you will notice a difference.

If you decide to cut the mast down then you will have to relocate at least one spreader. Either way you would benefit from getting advice from a naval architect (which is what I did before buying the mast).

Greg

[AndyEss]

With a full keel boat, I’d probably just keep the taller, heavier cross section mast, especially if new sails were part of the change over.
Reef sooner, keep more supplies, spare parts in your bilge.
With the cost savings of not modifying the longer mast you so easily found, change your FLA batteries to lithium to get a significant reduction in weight probably above your CG

[ahun]

In Darwin. We lost the mast on the way back from the Kimberly.