Driving a cat?

[airlock]

Hello again,

My search for the perfect little cat is ending as i've found two strong contenders one of which will most likely be coming home some time soon pending mechanical inspection and the usual haggling.

I've hunted around online for a definitive guide of how to drive these boats to get the optimum performance, ride and safety and while i've been able to turn up some useful information about weight and trim sensitivity, many of the opinions on exactly when to trim which motor differ quite a lot. Could someone with who is experienced and confident with the smaller twin hulls give me a few pointers on how to get them running well and safely.

So far i've come across the following points, some i'm not to sure on:


avoid head on approach in both following and head seas, use a more angled line, How much of an angle and in what swell direction?
trimming the motor on one side lifts the nose of the opposing hull, This seems a little counter intuitive to me, is it correct?
Trim the motor up on the side the swell is coming from, lean slightly into the waves.
Keep speed up in rough conditions to keep air in the tunnel, slowing down is a big nono


Could someone confirm or correct these points and add anything else important.

My other concern is the change in approach to bar crossings compared to a mono hull?

Any help would be a hugely appreciated, I love the way these boats ride when driven correctly and the less time i spend scaring myself shitless figuring this out the more time i can spend enjoying the thing.

[Fed]

avoid head on approach in both following and head seas, use a more angled line, How much of an angle and in what swell direction?


Wrong




trimming the motor on one side lifts the nose of the opposing hull, This seems a little counter intuitive to me, is it correct?


Yes.




Trim the motor up on the side the swell is coming from, lean slightly into the waves.


Yes that works but you will have to get a 'feel' for it.




Keep speed up in rough conditions to keep air in the tunnel, slowing down is a big nono


That works to a point but when you're forced to slow down because it's too rough they turn into dogs.
(Worse than monos)

I had a super trim sensitive 16' Sharkcat for 15 Years and the only thing I never managed to do was roll it over but I came close a few times.

Take it easy & do a lot of experimenting along the way, you're still going to get caught out but they're very forgiving after the scare the crap out of you.

Popcorn anyone?

[Crocodile]

Hello Airlock,

I have a 4.3m Webster Twinfisher, about the smallest cat there is.
I have only one motor so the lateral trim by two motors is not applicable.
It is very sensitive to fore and aft trim and small adjustments of trim make big changes to ride and wetness.
I am always surprised at how often bow up trim works better than bow down when going uphill.
Downhill bow up trim is the go.
When it gets too rough to plane, mine really does not pound as badly as might expect.
The Webster has never given me a fright and I feel totally safe.
I am aware that it only weighs half a tonne, which is pretty light when at sea.
As for bar crossing, in my little cat the techniques are really the same as a small mono.
I think that you are over-thinking, cats really look after you not the other way round.

[Lovey80]

Airlock, what little cat did you settle on?

[airlock]

I'm tossing up between the 5.2 cairns custom craft i originally dismissed, after an inspection and bit of a reality check about what i needed and could manage it seems a good fit, the other is a 5.2 kevlar cat from an old boy down the road, however its my second choice as its got a set of old thirsty 2 strokes on the back and a little over budget. It'll come down to mechanical inspection's and final negotiations really.