Homebuilt

This thread is for the homebuilders out there.
I would enjoy hearing about your projects.
I started with a list of things I needed a boat to do and ended up with a 64’ power tri

Boatgm,
She looks all business to me.

How many hours have you logged in her so far?
Are the amas large enough in beam seas?
How much wave piercing have you done?
Power and speeds?
Tell all.

manyboats said:

Boatgm,
She looks all business to me.

How many hours have you logged in her so far?
Are the amas large enough in beam seas?
How much wave piercing have you done?
Power and speeds?
Tell all.

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1000's of miles over the past few years.
I have a change to the amas on my “to do list”. They have too much initial buoyancy making the ride stiff so I thought I want to narrow then up, when I get some time.
If I do it again I think I could live with a single outrigger.
Big waves have been comfortable both up wind and down. Downwind the speed can be used to keep you on a single wave for miles if one cares to drive, its great fun. The anchor stows aft when I am running. I have had the parachute out. It ride well in big waves once you get the angles right.
Top speed is currently 23 knots, 20 knots is about a liter per mile, 15 knots is about half that and I don’t think it burns fuel at 8 knots.
The engine is a 4 cylinder yanmar. The cabin is air conditioned with a simple automotive system with AC coming from inverters. My get home is a long shaft 6 hp 4 cycles outboard it charges at 6 amps, and steers with the autopilot and pushes us along at 6 knots, but that was not in any wind to speak of, just testing.

Where there's a will there's a way

Boatgm,

Incredible efficiency. Great. Goes to show when there's only 1/10th as much oil available we'll still be able to go powerboating!

Re the amas. Another solution could possibly be to just raise them 2" or so. On my sorta tri my outboard hulls were 3" above the center line keel and if I had it to do over again I'd raise them an inch. I suspect that small differences in vertical placement makes big differences in stability characteristics. Also the placement fore and aft must have an effect on the boats ability to quarter seas from either direction. For, aft or amidships.

Are you on BoatDesign.net? They have a great section of threads on multi-hulls.

Thank you

Thank you for sharing your experience and suggestions, I have changed the height, the problem come in the specific way I use the boat. outbound I am loaded up with fuel and tons of books and come home light. My displacement can change over 100 % so it’s hard to get the height just right. As a compromise I was thinking about very narrow amas but deeper , they will always be in the water but not have so much boyamcy as to stop the rocking. I knew I was in trouble when a bunch of old fats guys (including me) stood on an ama and it didn’t sink much. Thank you for the BoatDesign.net link, I have been there.

Boatgm, the lines of you vessel remind me a bit of the round the world record setting hi-tech tri called (then) Earthrace, later rammed and sunk while working for Sea Shepherd under the name of the designer/maker, Ady Gil, trying to protect Humpbacks from the Japanese whalers. I suspect I will not be the first to make the comparison. Of course you don't have those fancy wings, but....
Japanese Whalers Ram Sea Shepherd Ship Ady Gil : Indybay


PS, as an aside, and for the benefit of others like me annoyed by the wind rumble, that is very hard to avoid when using these new digital video cameras, (evident on this video and always a factor out on the water). Remember how older cameras had a separate mike attached with a foam sock over it that prevented the same problem. These modern mics are just inside holes on the front of the thing, and like mobile phone mics, incredibly sensitive. I found this last month while filming the grandkids activities, that sticking a strip of Micropore tape, then a layer of tachy-backed foam rubber over the mics works well.

Yea I'm a kid in a candy store at BoatDesign.net

How about much larger amas shaped like a V. About 1/3 the size of the hull. But like you say the way you use it will present a problem for any boat light and efficient. My tri was only happy running VERY light. It was magic then.

Here it is in 1973 near Juneau Alaska. She ran very smooth at 13 to 15 knots w a 55hp 3 cyl Johnson OB. I may build another.

The name "Carabao" is Tagalog (main language of Philippines) for water buffalo. I`m guessing this is a solidly built boat that loves water.
And yes Peter,she looks remarkably like Ady Gil; avoiding Japanese whale killer explosive harpoon boats is highly advisable.BruceK

Japanese whalers

I get that comparison all the time, I guess they copied me.
I will stay clear of all Japanese whalers.
thanks

Very cool boat, do you think its possible on a build that size that it could be a comfortable liveaboard?
1 King or queen size bed
1 sizable lounging area
1 Good sized shower/toilet area
small galley down as most will be done topside
and a decent sized well shaded cockpit

Ah, just found this http://www.islandcarabao.com/boat.html
I'm guessing not on this actual boat but maybe one a bit fatter and not as fuel efficient

FF said:

20 knots is about a liter per mile, 15 knots is about half that

Thats at least 4X better than even a well designed a roomaran.

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It also has about a 1/4 of the living space.

I would also disagree with your assertion of being 4x better on fuel as there are more than a few live aboard power catamarans that get 1litre/nm.

Here is one

Chamberlin 46 Power Cat
This Robin Chamberlin designed power catamaran is a true blue water cruiser with the ability to do long passages in luxury and comfort. Her amazing fuel economy of 1-1.3L/nm, large fuel tanks and outstanding seaworthiness allow her to travel with ease. The current owners have taken her to New Caledonia, to the bottom of Tasmania through southern ocean swell and to the Kimberly’s.

Chamberlin 46 Power Cat | Multihull Yacht Sales Australia

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In the displacement world I don’t think there is a best design. Some of the multihulls can push the hull speed number a bit over 1.34 but most of the gain comes in the fact that the displacements are low and the waterline lengths are long. The hp/ton number at a given hull speed is difficult to get around. My tri works because it’s a cargo boat and has a wide weathers range, so living on this boat was not a main concern. It’s comfortable for what it does, but I don’t think I would want to take two couples out for anything longer then a sunset cruise. That said I have no problem leaving the dock in a blow and ending up 200 miles down the road in just half a day with the air-condition on and hot chow .
I think all boat are the “right boat” for something - the hard part is to understand ones true needs so you can find that right boat.
My next boat will carry medical teams of ten persons plus crew. This boat is a mono hull, the way to keep fuel consumption low is to operate at a low s/l ratio, and to keeping the displacement low. I expect this will be a 12 knot boat. All boats are the right boat

>I would also disagree with your assertion of being 4x better on fuel as there are more than a few live aboard power catamarans that get 1litre/nm.<

AT 20 K????,,,,,,,, I doubt it!!!!

more likely under half that speed , like most displacement boats.

At speed weight is also a concern and the single hull with outriggers will probably be under half or 1/3 the weight of a std cruising Cat.

FF said:

>I would also disagree with your assertion of being 4x better on fuel as there are more than a few live aboard power catamarans that get 1litre/nm.<

AT 20 K????,,,,,,,, I doubt it!!!!

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Compare apples with apples.
You have a comfortable liveaboard cat Vs a very skinny hull that probably doesnt have room for a lounge or a queen size bed.
Its like comparing a motorbike to a motorhome

Dont get me wrong, it is a very impressive vessel, but she is limited as far as a liveaboard is concerned.

more likely under half that speed , like most displacement boats.

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Try again.
13.5 knots was the average speed for its Brisbane to Tasmania fuel usage test.

"On a fuel consumption test between Brisbane and Hobart without refuelling en-route and cruising between 13 and 14 knots, it achieved a staggering 1.3 litres per nautical mile economy."
MultiMarket - Life After Sailing Cats

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Thats around 1100 nm miles if you were wondering.

At speed weight is also a concern and the single hull with outriggers will probably be under half or 1/3 the weight of a std cruising Cat.

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of course it is
It is half or even 1/3rd of the boat

I'm not really sure what your point is?