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Old 15-01-2013, 14:17   #1
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How much will shortening mast affect performance?

Saw a nice boat for sale but the owner cut the mast 7ft so it can do the ICW. A sloop rig. Any thoughts on how much that will affect performance on a 50 ft boat?
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Old 15-01-2013, 14:36   #2
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Re: How much will shortening mast affect performance?

that is a question for the naval architech, that designed this boat. there is a question of sailplan balance.
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Old 15-01-2013, 14:37   #3
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Re: How much will shortening mast affect performance?

Wow that's quite a reduction. I'm guessing it was a fractional rig, and he cut it just above the jib head and it is now a masthead rig? And no reduction in boom length?

I say the seller should expect to take a bad hit on the price for mutilating the mast. The boat will be a lot stiffer and probably a bit slower.

You could convert to a gaff-head rig and gain back a little of the sail area you lost but she will carry maybe a bit more weather helm. You could add a small topmast and a fisherman's topsl maybe. That and the gafftop main will give you a net increase in sail area. You won't get back all of the windward performance that the boat lost, but she will do great running downwind or reaching.
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Old 15-01-2013, 14:39   #4
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Re: How much will shortening mast affect performance?

Cut off 7'

If it started out with a 400 sf mainsail it would reduce it by 117 sf +/- leaving 283 sf. Pretty much like it were on a second reef. Then there's the jib/genoa. Don't think is would sail very well in anything less then 15 kt.
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Old 15-01-2013, 14:45   #5
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Quote:
Originally Posted by delmarrey View Post
Cut off 7'

If it started out with a 400 sf mainsail it would reduce it by 117 sf +/- leaving 283 sf. Pretty much like it were on a second reef. Then there's the jib/genoa. Don't think is would sail very well in anything less then 15 kt.
In my opinion you cannot calculate this without knowing at least the length of the boom...
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Old 15-01-2013, 14:50   #6
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Re: How much will shortening mast affect performance?

You could calculate the sail area to displacement ratio and compare the result to the original design. Might give you a ball park idea of how much performance was reduced. You could also use the number to compare other like designs with similar SA/Disp ratios to see if it might be acceptable to you.

Seems like a lot of mast was cut out of the equation .........
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Old 15-01-2013, 14:50   #7
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Re: How much will shortening mast affect performance?

Quote:
Originally Posted by Alecadi View Post
In my opinion you cannot calculate this without knowing at least the length of the boom...
Did you notice the word "IF"?
This is just an estimate related to my own boat as a reference, since the OP didn't give any dim's.
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Old 15-01-2013, 15:05   #8
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Re: How much will shortening mast affect performance?

Bottom line is that the affect could be quite drastic. Hard to know for sure without a lot more details. Like GrowleyMonster said, the sales price of the boat has to take a pretty serious hit for such a change. I would probably look at the price of similar boats and then knock at least $8k-$10k off for the whack-job on the mast.

And that really is AT LEAST! Depending on other circumstances, the whack-job on the mast might be worth taking as much as $20k-$25k off the sales price.

This is a good example of why it is stupid to buy a boat that is not what you want, and then try to make it what you want, when you could have just bought another boat in the first place that WAS what you wanted. The owner of the boat should have just bought a boat with a shorter mast designed into it, if that was one of his criteria. There are lots of different boats out there with masts plenty short enough for the ICW. He whacked a huge chunk out of the resale value of his boat when he whacked that chunk off of the mast.
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Old 15-01-2013, 15:19   #9
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Re: How much will shortening mast affect performance?

Quote:
Originally Posted by denverd0n View Post
....

He whacked a huge chunk out of the resale value of his boat when he whacked that chunk off of the mast.
Unless, of course, he sells the boat to someone who wants to swan up and down the ICW too!

It would help us to give useful advice if the OP told us what design the boat is... otherwise we're just shooting in the dark and pontificating (as usual).

Cheers,

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Old 16-01-2013, 03:06   #10
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Re: How much will shortening mast affect performance?

Absolutely correct, but I think as a general principle that the sort of person who thought this was a cunning plan is probably not the sort of person whose other cunning plans I wish to purchase.

"My coat's arms are too short, so I cut the first joint off every finger. For the win!"
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Old 16-01-2013, 03:49   #11
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What ever happened to the 7 foot section? Is it on the boat owner's dinghy?

Why 7 feet and not 8, or ten?

The owner who wanted to sail under bridges solved his mast height challenge. Bravo.
For most sailors, there is something diminutive and belittling about the act of cutting a mast.

There are sailors at my marina who seek out mast measurements because they believe bigger is better. On occasion, I have seen them walking about with a 100 foot tape measure. In one case an argument ensued because it wasn't about the biggest mast but the length of the boom as the debate went on and on... For weeks.

Sail area is considered the power part of the equation for speed. Here the power is reduced by a smaller mast to suit a smaller sail. Without going into details, one could deduce that the boat would be slower, heel less, and be slower to respond to wind changing conditions than its original mast was design -- for its proper size sail.
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Old 16-01-2013, 07:03   #12
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The reduction in mast height would probably alter the sail balance as noted by others but maybe the headsails or boom length has been changed to compensate? If not, this is probably that could be done. Need to go back to the original design .
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Old 16-01-2013, 14:40   #13
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Re: How much will shortening mast affect performance?

Is it possible that the boat in it's original form was designed for light weather performance, and in the place it was currently used was always overpowered with a full main, in which case lopping off some mast length might be a plus rather than a negative? Just thinking!
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Old 16-01-2013, 14:59   #14
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Re: How much will shortening mast affect performance?

Quote:
Originally Posted by KiwiIC View Post
Is it possible that the boat in it's original form was designed for light weather performance, and in the place it was currently used was always overpowered with a full main, in which case lopping off some mast length might be a plus rather than a negative? Just thinking!
We would have to know what he/it really has left. So far, there's been no reply from the OP.
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Old 16-01-2013, 15:02   #15
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Re: How much will shortening mast affect performance?

Does anyone even know what make/model we are talking about?
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