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Author Topic: Mast Length?  (Read 329 times)

Brian60

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Mast Length?
« on: June 11, 2018, 09:14:22 AM »

As my main build ground to a halt, I returned to my pond yacht which has been consigned to a cupboard top for 5 months :embarrassed: :embarrassed: 


The hull is completed but the plan I was working from had no details on mast length, its only a pond yacht so nothing has to be specific or exact, not as though its entering any competitions  :}  So the question is, is there a length of hull to mast height ratio to work at or is it down to 'it looks right so it ok?'


I did see someplace that a rule of thumb is hull length plus a third more. I've done that but it looks way too tall for this hull. Its 22 inches long, so I made the mast 32 inches. It looks better at 27 inches, but before I go pruning I'd like an idea to work to please.

tigertiger

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Re: Mast Length?
« Reply #1 on: June 11, 2018, 12:01:28 PM »

If you have the plans, is there a sail plan, from which you can glean some ideas. For example, if the bottom part of the mainsail is shown, you could extend the lines, then add a bit for the up-haul halyard. Or any lines from the fore stay or back stay.
You could also get some ideas of scale of you do a photo search on google, if you know the name of the model. Or a rough idea of ratios by looking at photos of other pond yachts. When comparing photos, you should also compare keel types, some have small keels and relatively short masts. Others long keels and long masts.
Other than that, the rest of your thinking seems logical. If the mast is too tall, you will carry to much canvas and the boat may heel more than you want it too.
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exvtop

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Re: Mast Length?
« Reply #2 on: June 11, 2018, 12:24:24 PM »

The Micro Magic is 21 inches long and mast height of the main rig is 29 and a half inches.
Should think 29 to 30 inches for yours would be about right.


Mike
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KitS

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Re: Mast Length?
« Reply #3 on: June 11, 2018, 12:41:22 PM »

My Minimum has a 31" hull length and its 1M storm suit mast is 41" tall, so that's a 1:1.3 ratio.

In truth it's a tad undersailed for light winds, viz being stuck in the middle of the lake at Wicksteed y'day for some time, but it works most days.
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Regards
Kit

Brian60

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Re: Mast Length?
« Reply #4 on: June 11, 2018, 01:44:09 PM »

OK thanks for the replies you guys. Sadly it was just a set of frame lines with no other info, not even a model name. I have seen similar while searching google. I did some time ago start a build log in the yacht section above, as per that you will see it has a shallow but long and bulbous keel. I think it may have just been drawn by someone as a 'suck it and see' idea.


Looking at the length of the mast and the amount of lead I could get into the keel I reckon it may be prone to capsizing in any but the lightest of winds. I think I may even cut off the keel and make it deeper.

Brian60

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Re: Mast Length?
« Reply #5 on: June 11, 2018, 02:59:43 PM »

I've done some more digging via google and found that it was model based on a 1920's 6metre class. The plan can possibly be obtained from a chap in Scarborough. More digging might turn up some views of it - I really don't need the plan now the hull is built {-)

rickles23

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Re: Mast Length?
« Reply #6 on: June 11, 2018, 03:55:20 PM »

Hi,


I use the rule of thumb of 1.5 X boat length.

There are, of course, many variables as to mast length: working sail set or topsail set.

Regards
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Brian60

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Re: Mast Length?
« Reply #7 on: June 11, 2018, 05:36:04 PM »

I managed to source a drawing of the model with sizes! I did some mathematics and the end result for my hull length is a whopping 38 inches!


The original model was built with a LOA of 68 inches and a mast height of 56 inches from the deck. This is 6 inches taller than what I already have. It just looks out of kilter. I'll stick with the 28 inches which looks in proportion at least to my eye.

rickles23

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Re: Mast Length?
« Reply #8 on: June 11, 2018, 06:10:55 PM »

Hi,


My racing Marblehead is 50 inches long (I still use the original measurement) and the top set of sails require a 7 foot mast.  Regards
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tarmstro

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Re: Mast Length?
« Reply #9 on: June 11, 2018, 09:16:34 PM »

1.5x LOA is for real-size sailboats.
For RC models I'll go for 2x LOA for light air set of sails (RG65's are 65cmLOA, have 130cm high mast for A-sail set).
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