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Old 28-05-2015, 18:21   #1
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Mast Aft

You see a few cats these days with the mast set well aft on the bridgedeck - primarily with Lagoons, but on some other lower profile builds and custom builds. The proponents argue that a higher aspect ratio main, a larger headsail, moving the CoE aft and easier-to-handle rigs are benefits. The drawback is a more complicated structure to place the mast foot on top of the coach house. I spoke with VPLP and they confirmed this view. (NB: Isn't it refreshing that a major designer like VPLP will talk with the owner of one of their older, out of production designs. Five thumbs up for them).

On the other hand, there is a Lagoon 39 in this marina and the boom looks like a toy. With the elevated cockpit, the rig looks like something on a trawler. I can't imagine it sails very well, but maybe that is not its intended purpose.

Any thoughts on this trend? Do you think it provides better performance, or is it primarily to allow for more salon space?
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Old 28-05-2015, 18:31   #2
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Re: Mast Aft

You mean like these new fangled things?
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Old 28-05-2015, 22:23   #3
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Re: Mast Aft

I was actually thinking more along these lines.
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Old 29-05-2015, 01:22   #4
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Re: Mast Aft

Quote:
Originally Posted by SVNeko View Post
You see a few cats these days with the mast set well aft on the bridgedeck - primarily with Lagoons, but on some other lower profile builds and custom builds. The proponents argue that a higher aspect ratio main, a larger headsail, moving the CoE aft and easier-to-handle rigs are benefits. The drawback is a more complicated structure to place the mast foot on top of the coach house. I spoke with VPLP and they confirmed this view. (NB: Isn't it refreshing that a major designer like VPLP will talk with the owner of one of their older, out of production designs. Five thumbs up for them).

On the other hand, there is a Lagoon 39 in this marina and the boom looks like a toy. With the elevated cockpit, the rig looks like something on a trawler. I can't imagine it sails very well, but maybe that is not its intended purpose.

Any thoughts on this trend? Do you think it provides better performance, or is it primarily to allow for more salon space?
On some vessels it is giving better performance and there are other designers that have gone to center mounted masts and weight for stability as well. Larger genoa and smaller foresail. Likely to see more of it. Works well. Need to engineer the support for the main however. certainly can be done.

Some Other designers.

Freeflow FreeFlow Catamarans

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Old 29-05-2015, 01:34   #5
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Re: Mast Aft

The Beiker 53 seems to have fairly centrally located mast also.

Bieker 53 - Exciting high performance cruiser

http://sailinganarchy.com/2014/08/21/crossbow/

http://biekerboats.blogspot.com.au/2...cting-b53.html
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Old 29-05-2015, 02:46   #6
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Re: Mast Aft

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Originally Posted by SVNeko View Post
Any thoughts on this trend? Do you think it provides better performance, or is it primarily to allow for more salon space?
If you take the Lagoon 39 as an example, these are not meant to sail.The 39 is very heavy with a very small rig. The rig is easily manageable and foolproof. Thats what counts in the charter market.
May be Ok for tradewind sailing, if you have enough diesel for the upwind legs.

To me it looks like an experiment to see what compromises the market is willing to accept. And if you look at the few 39 threads here it has not really taken off. So far I have seen only 2 of these both in charter.
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Old 29-05-2015, 05:39   #7
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Re: Mast Aft

SVN,

As you have summarised correctly, there are benefits to the aft mast position, but just plonking the mast in that position does not mean it will a great solution, without, as you say, consideration to the engineering required. I cannot figure out how the Lagoon 39, or 52 for that matter, are engineered & built properly to support it, and got no answers when asking about it from Lagoon. If you have a pipeline to VPLP, I'd be curious to hear their answer.e

By the way, VPLP saw Nathan Stantons FF52 being built in China by an owner, and subsequently the Lagoon boats appeared, but that's another story.

I have researched this fairly extensively, and IMHO the Stanton boats are properly designed and built to carry the mast in that position. In fact,they are specifically designed & built to do this, and the structural and composite engineering to pull it off are not easy peasy.

But to my mind, it is worth it and one of the reasons we chose the FF46 as our design, after considering pretty much everything else.

It sails beautifully on all points of sail, and especially through rough water. FWIW, I spoke with owners of an FF52 who went through a brutal test sail in big, short chop, and they said they had never sailed on a boat that performed nearly as well, and they put their deposit down immediately after the test sail. They had test sailed every boat I know of over the previous 3 years looking for their ideal circumnavigation liveaboard, and settled on the Freeflow for 1, the performance & 2. the sail handling advantages of the wishbone aft mast rig. No traveller loads, easy manual sail handling by a cruising couple, even elderly vintage types like us.

There is one disadvantage and that is, compared to a Bermuda/Marconi rig, it is not a raceboat for close reaching upwind courses, compared to a large roachy main driven boat with smaller flat jibs. But for cruising, it is excellent.

Beware of aft mast boats without the proper engineered solution. And BTW, the reference you made to the champher panels being carried back on the bridgedeck are part of the engineering solution, and they soften the ride in lumpy confused seas, as well as give great bouancy lift on downwind surfing conditions.
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Old 29-05-2015, 06:27   #8
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Re: Mast Aft

I thought the mast in the middle of the boat was a true cutter rig, developed many years ago to facilitate single handing.
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Old 31-05-2015, 23:37   #9
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Re: Mast Aft

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

Flying Fish 45 - Grainger Designs Performance Multihull Yachts
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Old 01-06-2015, 06:00   #10
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Re: Mast Aft

Reminds me of Phil Bolger's all-staysail rig. . . .
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Old 01-06-2015, 07:55   #11
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Re: Mast Aft

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Originally Posted by BigBeakie View Post
I have researched this fairly extensively, and IMHO the Stanton boats are properly designed and built to carry the mast in that position. In fact,they are specifically designed & built to do this, and the structural and composite engineering to pull it off are not easy peasy.
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.
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Old 01-06-2015, 08:29   #12
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Re: Mast Aft

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Originally Posted by SVNeko View Post
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.
I suspect the issue is cost to manufacture and not engineering issues.

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Old 01-06-2015, 08:49   #13
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Re: Mast Aft





Lagoon 39?

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Old 01-06-2015, 09:11   #14
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Re: Mast Aft

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Originally Posted by SVNeko View Post
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.
The mast simply extends down through the saloon to a dolphin striker, no?
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Old 01-06-2015, 11:02   #15
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Re: Mast Aft

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The mast simply extends down through the saloon to a dolphin striker, no?
I doubt any go through the cabintop. Probably better to step on top and use a compression post. Not sure what your reference to dolphin striker is. There wouldn't be any there. Would need a bulkhead to keep the boat from folding up also. Maybe the little Lagoon doesn't generate as much twist.
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