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Old 09-02-2013, 10:48   #1
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Mast Extension- How to Splice on an Extra 5'?

I want to extend a cruising-rig mast to the tall-rig length, which is about an extra 5'. What is the best way to go about doing this?

FWIW, this is on a 1974 Grampian 30.
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Old 09-02-2013, 10:58   #2
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Re: Mast extension- how to splice on an extra 5'?

Most I've seen use an inner sleeve structural epoxied and extensively riveted to the two outer pieces. Welding an option too. I saw one made and the rigging company ordered a short chunk of the original mast type, the split it and made it to fit inside the mast as a doubler. Placement of the spreader location isnt super critical on a conventional rig. ( I once had an analysis performed (by a noted marine architect) of a rig I self designed before I had it built. We discussed at length spreader location. Plus or minus a couple feet either way was not a big deal really.
It sounds like a lot of expense for small gain really though.....;rigging, sails, mast work....
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Old 09-02-2013, 11:11   #3
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Re: Mast extension- how to splice on an extra 5'?

A few feet for movement of the spreaders is not a big deal but he's talking 5' which is a big deal. Plan on relocating the spreaders to split the difference. Should do a check to be sure lower shroud angles don't get less than 12 degrees or compression loading could be an issue.
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Old 09-02-2013, 11:19   #4
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Re: Mast extension- how to splice on an extra 5'?

It's probably not worth the expense, but is still something I am considering. There is no headsail with the boat so getting a new (used) one slightly bigger than the old one wouldn't cost any extra. I am planning to add a bow-sprit and stay-sail as well, to get the rig to the largest incarnation that this boat came with from the factory. Light air predominates my home sailing waters.

Would it be better to splice at the bottom of the mast, and relocate the boom, than splice at the top of the mast and relocate all the mast-head fittings? I'd have to relocate the halyard winches as well, but right now there is only one very crappy winch on the mast so I plan on installing two new ones anyway.

Found a great webpage about splicing a mast!
http://www.svdreamtime.com/mast_rebuild.html
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Old 09-02-2013, 11:25   #5
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Re: Mast extension- how to splice on an extra 5'?

looking at the rig on Sailboatdata, it doesnt sem to be a very low aspect main really. I'd leave it. If you want better performance, have a new main cut fuller and lighter and get the genny similar.
Not sure how the spreader move needs to be done, but 5 ft is maybe 12% more length on the mast, (?) moving the spreaders 12% (of 5ft) up would be maybe 8". Maybe not necessary. Lower shroud angle wouldnt change if left where is. Upper stays would change for the angle either side of the spreader though....
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Old 09-02-2013, 20:13   #6
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Re: Mast extension- how to splice on an extra 5'?

Since adding a bowsprit and stay sail will move the Center-of-Effort (CE) forward and possibly create a lee helm situation. This will need to be compensated for by adding area to the main. You might want to look at going to a full battened main sail to re-balance the rig. Increasing the height of the mast is just going to exacerbate the unbalancing effect of adding additional sail area forward. It is also a lot of work when sail selection will have the same effect.

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Old 09-02-2013, 22:02   #7
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Re: Mast extension- how to splice on an extra 5'?

The factory cruising main and tall-rig main are within 1 sq ft of each other, as the boom on the cruising main is longer. I'd be mixing the cruising boom with the tall-rig mast and gaining area in the main as well.

Not particularly worried about the bowsprit affecting sail balance because, as previously mentioned, this was a factory option:

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Old 10-02-2013, 06:25   #8
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Re: Mast extension- how to splice on an extra 5'?

You could consider:
1
a carbon fiber mizzen which, with a decent roach, would add 35 or 40+ sq feet and probably balance nicely with more staysail. You may like this more in heavy weather because jib and jigger is so forgiving (I've done it.)
2
an aft-pointing crane at masthead so you could get a lot more roach on the main, maybe even one of those square-topped rigs. (I haven't done it; just theory.)
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Old 10-02-2013, 11:33   #9
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Re: Mast extension- how to splice on an extra 5'?

Yeah, a couple feet of 'sprit really wont change that much balance wise. Frankly I think there are too many boats with too much weather helm. You might actually like a l ittle less. Just depends on the boat I guess. Still... wow a lot of $ for minimal gain...will you be making it a cutter setup also?
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Old 10-02-2013, 11:52   #10
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Re: Mast Extension- How to Splice on an Extra 5'?

consider adding a full battoned main with a lot of roach. Also get a 135 or 155 or larger genoa. You will get fine performance in light air but you won't seriously add to weather helm or over-turning moment or cost. Invite a good sailmaker to spend a day on the boat and talk about it.
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Old 10-02-2013, 11:53   #11
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Re: Mast Extension- How to Splice on an Extra 5'?

I'd add the new section near the bottom: sleeving the mast, if well done, will strengthen it in two places where it can well use it: at the gooseneck, and where it passes through the deck.

Splitting a piece of the same mast section into four quadrants for an internal sleeve, as Cheechako suggests, is just about the best way to go I reckon.

Don't let anyone talk you into welding (although you'd get away with it at the masthead, it's definitely off the menu down low, where the bending moment is high).

Selection of rivet material is important to long term success.
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Old 10-02-2013, 19:01   #12
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Re: Mast Extension- How to Splice on an Extra 5'?

With all the storm damaged boats in the Northeast from TS Sandy, I wouldn't screw around with splicing I'd just try to find a whole mast and boom from a totalled out boat and replace yours with it.

A splice low down will put less weight aloft and that would make it the better way to go, unless the position of the boom and resulting loads on teh splice became an issue. Which might mean the best way to go was to put the splice down low, but clear above the boom even if that meant buying a longer piece of mast.

Which comes back to just buying the rig from a bigger boat, with an intact mast.

Either way you'll have to do custom rigging now as well. Grampians don't have a reputation for being light air boats. Once you add more rig, you may need to add more ballast to hold it upright as well. More work again, more $$ again.
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Old 10-02-2013, 19:41   #13
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Re: Mast Extension- How to Splice on an Extra 5'?

For what its worth, when I bought Magic the mast had parted at the spreaders from losing an upper while contacting a piling during a hurricane. I brought the mast to JSI spar shop on a trailer. The shop foreman looked out the door at the trailer and said Morgan 33 outisland, correct? It turns out that he built the mast back in the 70s. He explained that the mast had a weldment at the spreaders with a 2" splice done at the factory. The quoted price was $700 to fabricate the damaged section, sleeve and weld. I managed to find a hunk of the same extrusion at Dons Salvage. Ended up trading some canvas work for the repair. The welded section is the strongest part of the mast. Its full welded at the joint and holes were drilled and filled at increasingly greater centers and smaller sizes away from the joint. Been 9 yrs and many storms and hard sails later and holding up well. The guy at jsi mentioned the masts were immersed in a vat of concrete block sealer. He said this worked extremely well as he's watched his work over the decades with very little corrosion on the ones that were treated this way.
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Old 10-02-2013, 19:59   #14
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Re: Mast Extension- How to Splice on an Extra 5'?

It seems like it would be easier to do the bowsprit like you said and add a longer boom and a main with a full roach than to extend the mast.
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