Cats and Mooring

[Birdseye]

Re: why go so wide?

not true - or you would have cats that were wider than they were long.

when investigating, the southampton institute found that the area of the bridgebeck was a significant factor in stability - wind and waves getting under it. its also a significant factor in strength - a solid bridgedeck of narrower dimensions is much better than a wide netted bridgedeck. and cats have been known to break up.

in the end, you have to ask yourself why major manufacturers of long distance cruising cats (as opposed to med charter cats) often still go for the 2:1. and why, for example, there have been so few capsizes of boats like prouts and heavenly twins.

other factors are important. windage - height of bridgedeck clearance and of topsides. size of rig. keel design. resistance of bow to burying (ie trip over lee bow) and most important of all - sheer size.

any boat is a compromise but the one thing I have never wished for in my boat is more beam.

<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[snowleopard]

Re: why go so wide?

your profile is empty so don't know what you currently have.

within limits, the wider the beam the better resistance to over-the-beam capsizes. the ultimate righting moment is 1/2 beam x weight. boats like twins and prouts achieve the same righting moment by increasing the weight! other factors that keep the beam down in production cats are cost of production, expense of the extra engineering to get strength at a wider beam, customer resistance because of the marina problem and the need for a higher bridge clearance which restricts accommodation.

other factors can also cause a capsize of course, particularly stalling when sailing to windward causing a trip over the lee stern. 'silly' extremes of beam would bring these other factors more into play.

typical cats of the 60s & 70s had beams of as little as 15 ft on a 40 ft length while today's are typically 20-24 ft beam.

in the 70s i built a kelsall tri of 40ft x 23ft while my current cat from the same board has the same overall dimensions. derek is now of the view that with the wider beam of today's cats, they can achieve the stability previously enjoyed by tris and the third hull is now unnecessary (in cruising boats).

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[boatmike]

Re: why go so wide?

The resistance to capsize is NOT a beam related issue. Static stability of course increases with beam but most dangerous and most often capsizes recorded are caused by pitchpoling normally caused by burying the lee bow in a wave with a wavelength approximately equal to the length of the boat. In this case the greater the beam/length ratio the greater the danger of capsize in open ocean conditions. Prouts in particular are around 2.3 length to beam and tend to broach under these conditions rather than pitchpole. As a Snowgoose owner I am aware that there is no such thing as a perfect boat. They do tend to be on the heavy side, and the bridgedeck clearance causes a degree of slamming but statistics show they are extremely safe and if I have to chose seaworthyness against out and out speed that is OK by me.....

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[boatmike]

There are other production cats that are as safe as a Prout for ocean sailing and some are faster but the old Snowgoose has a brilliant blue water reputation for safety. My own Elite went around Cap le Hague (Alderney race) in wind against tide conditions on a spring tide last month in company with a Halberg Rassy 45ft (approx) A Westerly Oceanlord and a Fontain Pageot Cat of about 40ft. We all decided afterwards that we should have given the Cap a wider berth as the seas were horrible but the FP stopped dead 3 times with its bows buried, gave up and ran off to Alderney while we three carried on and anchored in Dixcart bay in Sark. Needless to say I got there first! There aint no way super light go fast cats can tolerate seas like that. Take your choice!

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[boatmike]

For the record I believe you are right on that but I still feel the Snowgoose, while a bit long in the tooth now perhaps is a good boat and on the safety front there are very few OF THE SAME SIZE to beat her. Most of the other boats, including the two you mention that are truly "blue water" boats are larger surely?

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[boatmike]

Or anywhere to sleep........

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[Birdseye]

In the final analysis the risk of capsize in a well sailed cruising cat is pretty small whatever the design type, probably less than the risk of sinking for an equivalent mono. But the problem of berthing a wide beam cat is an everyday problem and expense.

I sail cautiously with decent safety kit and do not worry about capsize. But I do worry about finding a suitable berth at the end of a long day, so I dont really see the point in having a wider beam than I need for accomodation and reasonable seaworthyness. But its a personal choice.



<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[boatmike]

Most cats (indeed I believe it would be true to say most boats) are not sailed in true blue water conditions where the seas seen today by the unfortunate, but thank God now safe rowers can happen at any time. Their skippers can therefore seek shelter long before experiencing extreme conditions. Nothing wrong with that and there is an argument in favour of fast sporty lightweight boats, cats or monos, for this kind of sailing. Who doesn't like going fast anyway? Those of us that venture offshore for any more than 48hours at a stretch however need to think about survival in extreme conditions. Personally I would not go 12 hours from shelter in a cat with the extreme beam to length ratios seen on some lightweight designs today anymore than I would go blue water sailing in any cat without a sea anchor or drogue. But then everyone is different and I am an old sailor not a bold sailor and it's only only mans opinion.... Wide beam cats can and do capsize in rough seas. But then you are quite right monohulls can suffer catastrophic damage and sink too. Personally I would like to continue to avoid either experience!

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[rickwat]

Re: Spanish Charges

Fair would be length x beam x draft. There should be cat corners of shallower depth and in tidal waters there should be outer marinas maintaining less depth of water or even drying so we don't have to wait for the gates to open for monos waiting to float their hidden appendages !

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