Switch to full time power?

[Bunji]

Originally Posted by Chotu

Yes. You can do this and have a displacement power cat. However, just leave the diesels. Why would you switch to outboards in this case?

Note: I HAVE an outboard powered cat and I think this is a bad idea. Lol

There are several well designed fuel efficient outboard powered catamarans (Asia catamarans), outboards are much lighter, easier and cheaper to both buy and maintain. They are a bad idea in your opinion because u chose the worst possible option (engines) and u have little understanding of hull speed

[Bunji]

Originally Posted by Bunji

There are several well designed fuel efficient outboard powered catamarans (Asia catamarans), outboards are much lighter, easier and cheaper to both buy and maintain. They are a bad idea in your opinion because u chose the worst possible option (engines) and u have little understanding of hull speed

Also there are no props and shafts, sail drives to worry about

[Chotu]

Originally Posted by Bunji

There are several well designed fuel efficient outboard powered catamarans (Asia catamarans), outboards are much lighter, easier and cheaper to both buy and maintain. They are a bad idea in your opinion because u chose the worst possible option (engines) and u have little understanding of hull speed

Our friend here was talking about taking a working sailboat with Diesel engines and using outboards instead, presumably pulling the diesels and shafts and putting outboards on the back after pulling the mast.

I HAVE an outboard powered catamaran. So obviously I would agree that there are good Outboard powered boats. What are you even talking about? If you’re going to do personal attacks at least try to have your facts straight. How dense are you anyway?

You apparently have zero understanding of hull speed. My hull speed is 20 ish knots.

With tiny outboard props instead of huge props to put the power to the water, I only get 8 knots under power.

Take a seat

[Tin Tin]

Powered Cat with twin 60 HP outboards, even has a mast and sail.
https://www.boatsonline.com.au/boats...tamaran/248725

[boatpoker]

Originally Posted by fxykty

Power boats are for being there; sailing boats are for getting there.

A large round italian sausage starting with the letter "B".

[Simi 60]

Originally Posted by Tin Tin

Powered Cat with twin 60 HP outboards, even has a mast and sail.
https://www.boatsonline.com.au/boats...tamaran/248725

Expensive for that.

[Bunji]

Originally Posted by Chotu

Our friend here was talking about taking a working sailboat with Diesel engines and using outboards instead, presumably pulling the diesels and shafts and putting outboards on the back after pulling the mast.

I HAVE an outboard powered catamaran. So obviously I would agree that there are good Outboard powered boats. What are you even talking about? If you’re going to do personal attacks at least try to have your facts straight. How dense are you anyway?

You apparently have zero understanding of hull speed. My hull speed is 20 ish knots.

With tiny outboard props instead of huge props to put the power to the water, I only get 8 knots under power.

Take a seat

To funny, your hull speed under power is not 20 knots, anybody that knows anything about sailing catamaran hull design (hull speed) speed at which the boat is most efficient at under power Will tell u that almost all sailing catamarans are only capable of 6 to 8 knots efficiently. (Sailing catamaran Hull speed under power). Some people’s choose to put bigger motors on there sailing catamarans, only to find all that happens is they squat more in the ass creating more drag (less efficient)
Reality is most people with sailing cats spend just as much time motoring (6 to 8 knots) as they do sailing because of unfavourable conditions(wind)
There is a well known designer (catamarans) here in oz who is often asked to design an efficient slow speed displacement power catamaran buy people who own sailing cats, his reply is to tell them to start the engine or engines. ( they already have and extremely efficient hull shape for motoring at up to 8 knots. Want to be more efficient, remove the stick (less drag) the winches, sails, rigging etc (weight) . 50 to 60 ft power catamarans are generally considered to big to be outboard powered, 36 ft max

[Bunji]

Originally Posted by MaddMatt

What is the big difference between part time motoring with sails and full time without?

I have no interest in sailing but love the catamaran look, layout, efficiency and handling. If i remove all the sailing bits, can i use a 30-40' cat with a couple of outboard 60hp engines?

Thanks. I appreciate the wealth of knowledge present here!

Matt

Gday Matt 60 hp is overkill, 2 x 20 hp extra long shaft honda full noise equals 10 knots, cruise on 1 engine 5 to 6 knots, most efficient at 6 to 8 knots depending on design, some have more rocker (early crowthers) than Others, more rocker more squat (40 ft). I changed (modified) the hull shape on ours, (Converted sailing cat to power)and in doing so removed much of the rocker And added about 200 kgs of bouancy to each hull aft, gained an extra 3 to 4 knots, cruise all day 10 knots 2 x 9.9 hp high thrust yamaha (12 inch prop) 20 to 25 litres, 34ft 3 ton. Your definitely on the right track in terms of choice regarding efficiency and all the other advantages that catamarans offer, beaching, shallow draft, light weight etc. cheers

[LargeMarge]

How large are your fuel tanks?

We looked at an aluminum sixty-foot residential power catamaran.
Nicely motivated by a pair of diesel inboards, at 'best cruise', the range is about six-hundred miles.

[mcarthur]

Originally Posted by LargeMarge

How large are your fuel tanks?

We looked at an aluminum sixty-foot residential power catamaran.
Nicely motivated by a pair of diesel inboards, at 'best cruise', the range is about six-hundred miles.

Lots of powercats have much more than that at 1.34x/1.2/1.1 hull speed! Out of my database, 41 configurations/boats can do >600nm range at 8kn but only 3 do less than 600nm.

Note that "best cruise" in some brands/boats means 16kn or something large! I'm talking down at "hull speed" (using the usual formula, despite the difference of that for narrow-hulled vessels).

[Bunji]

Originally Posted by LargeMarge

How large are your fuel tanks?

We looked at an aluminum sixty-foot residential power catamaran.
Nicely motivated by a pair of diesel inboards, at 'best cruise', the range is about six-hundred miles.

2 x 150 litre + 2 x 100 litre can carry more, 2 to 4 litres per hour cheers

[Simi 60]

Originally Posted by mcarthur

Lots of powercats have much more than that at 1.34x/1.2/1.1 hull speed! Out of my database, 41 configurations/boats can do >600nm range at 8kn but only 3 do less than 600nm.

Note that "best cruise" in some brands/boats means 16kn or something large! I'm talking down at "hull speed" (using the usual formula, despite the difference of that for narrow-hulled vessels).

But most simply can't carry the weight of fuel and gear.
Beholden to shops, fuel dock and marinas they be.

Very rare is the power cat that can carry the weight of fuel and stores to give them range and autonomy and the ones that do cost big BIG coin.

By range and autonomy I am talking about being able to cruise 6 months or longer without needing to find a shop or fuel dock.

[rslifkin]

Originally Posted by Simi 60

But most simply can't carry the weight of fuel and gear.
Beholden to shops, fuel dock and marinas they be.

Very rare is the power cat that can carry the weight of fuel and stores to give them range and autonomy and the ones that do cost big BIG coin.

By range and autonomy I am talking about being able to cruise 6 months or longer without needing to find a shop or fuel dock.

For the most part, carrying that amount of fuel and other supplies on a powerboat needs a big boat, regardless of cat or mono. Load carrying ability typically goes up disproportionately to an increase in size.