Following Seas and Cockpit Height

[44'cruisingcat]

Originally Posted by Training Wheels

It's always seemed to me that to be accurate, when comparing D/L ratios from monos to cats, the L for the cat should be for the total waterline length of both hulls, since the displacement is carried on 2 hulls.


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How about tri's?

[Training Wheels]

Good question! Sitting at the dock, all our displacement is taken by our main hull. Sailing, some of the displacement is transferred to a float, the amount dependent on the heeling moment.
Of course, if your catamaran is flying a hull, I guess you would only count one hull.......


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[44'cruisingcat]

The AC 72 must be variable displacement. They'd go from being ultra ULTRA lightweight racers, to heavy cruisers as they get on their foils...


Or maybe monohull definitions really don't apply to multihulls. Maybe a 45 foot, 10 tonne cat isn't light. Maybe a 45 foot cat that draws 1.3 metres isn't shoal draught. Maybe a 45 foot cat with a 20 foot beam isn't particularly beamy....

[Training Wheels]

I'm so confused!


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[Liam Wald]

Originally Posted by 44'cruisingcat

The AC 72 must be variable displacement.

Wouldn't you call the AC72 a planing hull rather than a displacement hull.
A ski boat displaces when going 5 knots but at 40 it is planing.
The ski boat is always referred to as a planing hull even if it is going slow and displacing.
Does the same hold true for sailboats that plane on foils?
Are Hobie Cats displacement boats?

[Training Wheels]

Hobie Cats are displacement hulls.

[boatman61]

I dispute the claim that for a Lagoon to exceed 10kts it needs to surf..
However.. for a Catalac to exceed 18kts.. yes it does...

[arsenelupiga]

Originally Posted by boatman61

I dispute the claim that for a Lagoon to exceed 10kts it needs to surf..
However.. for a Catalac to exceed 18kts.. yes it does...

Well, that is how far I got with my sailing skills, following lagoon reefing guidelines. Would love to be proven wrong though.

When started sailing L 400, I got excited when first time crossed 6 kn !

It is not like catana where plenty of sail area so trimming can be bad but still go fine.

[44'cruisingcat]

Originally Posted by Liam Wald

Wouldn't you call the AC72 a planing hull rather than a displacement hull.

No, it's a displacement boat with foils.

[avb3]

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[boatman61]

Originally Posted by arsenelupiga

Well, that is how far I got with my sailing skills, following lagoon reefing guidelines. Would love to be proven wrong though.

When started sailing L 400, I got excited when first time crossed 6 kn !

It is not like catana where plenty of sail area so trimming can be bad but still go fine.

The Lagoon was a 380 I had to take from Bari, Italy to Gran Canaria in time to meet the ARC timeline.. as we came past the SW corner of Sicily the wind got up to F8 from the NNW.. we had full reef in the main and 50% genoa and were averaging 11 to 12kts.. wind was maybe 15* fwd of the beam.. quite a buzz..
The other was a Catalac900 I was taking from the UK to E Spain.. had picked up the owner and his dog in Baiona and we were running down the Portuguese coast before a F7 gusting 8 from the NW.. 1/3rd genoa.. no main.. average surf was 14 -15kts.. then a real big wave came along and we flew.. 18.23kts and I started a serious pucker as we passed a 50* angle and started gaining on the trough..
Obviously we survived.. but the owner said afterwards my face was a picture.
Both owners were CF members..

[PacificGreen]

I found this topic interesting to say the least. I have some specific questions though that have not been addressed and also I did find an interesting video that seems to summarize the thread well.

I'll start with my question regarding outboards in following seas? I would certainly value some input on that topic and that is why I have read until the end of this thread and brought it back up.

I'd like to hear from anyone that can contribute to my knowledge of how to survive getting the outboards dunked or what the procedure would be especially during the wave pattern in terms of keeping ahead of the wave or if it is even possible with dual 9.9 outboards on a 3 tonne catamaran with no mast or sails?

https://www.youtube.com/watch?v=hQ-svmgOxqw

[mako]

This is an interesting thread and I enjoy seeing you sailboat boys arguing cat versus monohull. I wonder how these cats fair when running in severe or survival conditions. My displacement trawler had a cockpit with the coaming at least 5ft above water. We spent a few days running in 25-30 ft seas and were pooped continuously. That cockpit was a giant swimming pool. Foaming water. We had good scuppers and enough reserve buoyancy so it didn't affect the vessel too much.

I would imagine that as long as you kept your nice, light cat from broaching that you would do much better. However, if your plans called for Southern Ocean sailing then I would seriously rethink the sliding doors. Even 1/2" tempered wouldn't hold up to direct hits by the big boys.

However it's a bit confusing when you bring up the question about a 3 ton boat with outboards. That seems like a whole different category than the thread has discussed.

[arsenelupiga]

we have been motoring in 5m square seas. One had to hold seriously as movements quite violent.

And suddenly my wife says - water !!!

I looked around and we got 1 litre of seawater in cockpit. I think she was in shock as never seen sea water in cockpit.

There was also mono near by and smart and sailing. Mast fell down and 4 men motored proudly into harbour. Looks like no person injured.

I am sure there are seas that will fill cockpit and take out metal door, but certainly not as easy as some think.

[SV Windrush II]

The video above looks like my experience for 7 days straight when headed for Hilo Hawaii. Many times I had waves break over the cockpit and fill it up. Thankfully I have 2 cockpit drains and all disappeared before the next one would drown it again.
Several times I opened my hatch at the same time a wave came right through and soaked most everything in the cabin. When the weather is like that it's not much fun, especially when it lasts for 7 days!