Originally Posted by capcook
I have been wondering this myself... I don't think the Trawler/Motor sailers are very good designs, but was wondering if one could put more HP in a standard Cat and perhaps carry an additional set of props. One set for agressive motoring and another folding prop for sailing...
A lot of the sailing/motoring we are contemplating may be done with the Mast stepped (waterways and rivers), so we will want good motoring capabilities... Without a Mast, a sailing design would be much lighter. I was wondering if you could power say a 45' Orana or Lagoon to 15-18kts with say 100HP in each hull..
Malcolm Tenant told me that this will work to some degree up to around 10 knots, on larger cats but then they tend to squat down aft if going much faster
I would agree and have observed this on several cats who thought they could just up the hp = more speed.
This is what a lot of french early gen powercat builders did as they already had the hull moulds
What you really need to do is to reverse the rocker to the horizontal down aft, but then this would affect the sailing ability, how, I am not sure.
The typical Motor Cats carry around 200hp in each hull I believe, but are much heaiver... I do like the idea of having the ability to hi-tail-it if you need to but to also be able to enjoy the "zen" of sailing.... Thoughts ?
The typical motor cat is built to do 20 knots into waves so is built heavier
it needs bigger motors for this speed
it therefore uses more fuel
so needs to carry more
it needs more displacement
to carry more fuel, larger motors and heavier build so loses speed and efficiency
The attempt to fix this is bigger motors
then it needs more fuel
And more displacement
and around and around we go.
A sailing cat these not be
perhaps if you take a sailing cat that already performs quite well under motor, say 8 -10 knots for a light 50fter with 40hp motors
Then you reverse the rocker to help prevent squat in the 10-14 knots range
And limit yourself to these lower speeds
And only put slightly larger motors in, around 65hp, so fuel usage is still low
And didnt put all the expensive mast, sails
, winches etc on figuring that the capital outlay of these pays for a lot of fuel for the motors that you had already paid for, and no need for two sets of props
And if you had a low flybridge to steer from you will hear very little, if any engine noise
, so you still get the zen like magic carpet ride*
I wonder if anyone is building such a vessel?
* I took a powercat ferry
18mths or more back
It had 310hp x 2 and, when sitting up on the roof (no flybridge) you had to listen hard for engine noise
It was quite surreal cutting through the water
, 12 feet high at 16 knots with no noise