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Old 01-06-2015, 11:07   #16
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Re: Mast Aft

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Another highly respected long term cat designer using centrally located mast.

Flying Fish 45 - Grainger Designs Performance Multihull Yachts
An interesting design. Seems the whole cabin is moved aft. The only mention of the aft mast is: "With the mast aft at the 50% position the Flying Fish 45 has excellent motion in a seaway and can be driven hard in fresh conditions." I'd like to understand these dynamics better from real world experiences.
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Old 01-06-2015, 12:09   #17
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Re: Mast Aft

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Well, give us the results of your research on how it is to be done. It seems the Lagoons do it with a compression post. O Yachts have an internal bulkhead there. With some FEA to analyze the load it would seem a matter of primarily compression support with some beefing up to handle lateral loads.
GForce does it with a 200mm wide compression post that is seated on and bonded / thru-bolted to one of the two forward full width bulkheads. The mainsail lines can run inside it and then under the bridgedeck. The cabintop is solid in that area with a large pad on the outside where the integrated ball for the rotating mast is mounted.
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Old 01-06-2015, 20:19   #18
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Re: Mast Aft

Of course there is a compression post on the Lagoons, the question is, what supports it? Just a few layers of uni?

The compression loads are well understood ( and they are BIG), you don't need FEA to determine them.

How it is done on the FreeFlow cats is the IP of the designer and I'm not about to reveal all that.
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Old 01-06-2015, 20:31   #19
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Re: Mast Aft

The aft compression post is supported by the same thing that supports the forward compression posts, bridgedeck floor bulkheads.
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Old 01-06-2015, 23:18   #20
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Re: Mast Aft

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Of course there is a compression post on the Lagoons, the question is, what supports it? Just a few layers of uni?

The compression loads are well understood ( and they are BIG), you don't need FEA to determine them.

How it is done on the FreeFlow cats is the IP of the designer and I'm not about to reveal all that.
This might help without giving away the IP.
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Old 02-06-2015, 01:56   #21
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Re: Mast Aft

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This might help without giving away the IP.
Yikes...don't know about the saggy bit, looks like a dag,
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Old 02-06-2015, 02:02   #22
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Re: Mast Aft

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Yikes...don't know about the saggy bit, looks like a dag,
for the non aussies here...from wiki

"Dag - The literal meaning is a dung-caked lock of wool around the hindquarters of a sheep an abbreviation of "daglock"."
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Old 02-06-2015, 06:10   #23
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Re: Mast Aft

Dag, LOL. But is that an aft anchor designed in? Interesting but not sure I want following waves torquing it up.

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Old 08-06-2015, 12:21   #24
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Re: Mast Aft

The Isara 50 doesn't seem too far back and yet they still try and avoid its impact on the interior in a very novel way. I personally like the innovation.
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Old 08-06-2015, 12:50   #25
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Re: Mast Aft

I have seen a few of the Lagoon 39s, that you mentioned, for charter here in the Caribbean, as well as a LS4, that was rigged similarly. They catch your eye because they look strange, as you said the mainsail looks more like the staysail on a trawler. I presumed the large roller reefing genoa and small main made it it easier to handle for charterers.
Always liked the look of the Switch 51.

Bill
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