Aluminium catamarans.

[AKA-None]

A lot of weld distortion is due to welding practices

[zurk]

jupiter 2 / mumby cats are made of weak 4mm aluminum.

the plans you get can be built out of 1/4" (6.35mm) aluminum plate.
thicker plates have lower weld distortion.

[NevilleCat]

Originally Posted by zurk

jupiter 2 / mumby cats are made of weak 4mm aluminum.

the plans you get can be built out of 1/4" (6.35mm) aluminum plate.
thicker plates have lower weld distortion.

Mumby cats are built of light 4mm aluminium

The Bruce Roberts 13m cat (whoever may have designed it) displacement is 13 1/2 ton plays the Mumbys 8 1/2
that's 5 ton more, but probably similar to the standard charter cat

[etoimene]

Interesting topic. I was just checking Mumby designs a few days ago.

What about the heat in aluminium cats?
Plastic is a bit better isolation.

Do they become oven? :-)

[fillintheblank]

Originally Posted by etoimene

Interesting topic. I was just checking Mumby designs a few days ago.

What about the heat in aluminium cats?
Plastic is a bit better isolation.

Do they become oven? :-)

They fully spray foam them, so heat should not be an issue. But it means checking back side of the hull is next to impossible.

[Matt Johnson]

Originally Posted by etoimene

Interesting topic. I was just checking Mumby designs a few days ago.

What about the heat in aluminium cats?
Plastic is a bit better isolation.

Do they become oven? :-)

Monohull - but even with 2" of spray foam insulation our aluminum boat was hotter than our previous balsa cored fiberglass boat.

If you paint the boat white instead of leaving it raw aluminum, it will be much cooler. There was a pretty shocking difference between our painted deck (Horizontal to the sun) and the aluminum hull (Vertical) in the Caribbean.


I'd also recommend an EVA foam decking material instead of painted decks. We could always walk bare foot on the fiberglass boat, but any really sunny day required footware on deck of the AL boat. EVA foam would fix that too ... and add a bit of extra insulation below deck.

Matt

[Macdyver]

Does anyone have pics of real builds of the Bruce Roberts 13 or 15m? Always been a monohull sailor, but with all the dive gear that I lug around, the square footage of a cat is starting to sound appealing.

[Matt Johnson]

Originally Posted by Macdyver

Does anyone have pics of real builds of the Bruce Roberts 13 or 15m? Always been a monohull sailor, but with all the dive gear that I lug around, the square footage of a cat is starting to sound appealing.

If you go to the Facebook group of DIY Catamarans, there is a guy building a Eurocat 1300 in aluminum. He's just started skinning the boat, but it's the most I've seen accomplished of these designs.

Maybe send a message to Bruce Roberts to see if any have been completed?

Matt

[Garrett Reid]

There is an 2002 aluminum 47 foot catamaran for sale in Spain, the builder was Yapluka out of Germany apparently. Nice boat but way way overpriced imho. Can't find any info on the builder, does anyone know about the origins of this build?

[jmh2002]

Originally Posted by fillintheblank

Mumby/cypher cats are also AL. check out the below channel, he has a vid series where he visits his boat as its built. At one point he states its costing him 300k, for a 48 footer. I am not sure how much that has changed, or what it came with for that price...

I think he said it would be closer to USD 400,000 now.

[Factor]

Originally Posted by zurk

jupiter 2 / mumby cats are made of weak 4mm aluminum.

the plans you get can be built out of 1/4" (6.35mm) aluminum plate.
thicker plates have lower weld distortion.

If 4mm is weak I am buggered if I know how planes stay in the air. Boeing jet liner is 1mm aluminium. So apparently you can build stuff out of light materials and have reliability and performance, indeed you must build lighter to have performance

[SV WELDER]

Originally Posted by Factor

If 4mm is weak I am buggered if I know how planes stay in the air. Boeing jet liner is 1mm aluminium. So apparently you can build stuff out of light materials and have reliability and performance, indeed you must build lighter to have performance

How many rocky shores do they smash a Boeing against on a regular basis?

[Sailmonkey]

Originally Posted by SV WELDER

How many rocky shores do they smash a Boeing against on a regular basis?

How many rocky shores does the average boat smash into?!?!

[dannc]

One can't judge the "strength" of a metal hull just by plate thickness.

The "strength" of a metal boat is a combination of plate thickness, it's material, along with the structure behind the plate, it's size, shape, number and material.

One can have thin hull plating but increase the size and number of the frames, longitudinals, and possibly bulkheads and still have a "strong" hull. Conversely, one could increase the thickness of the hull plating and decrease the size and number of frames, longitudinals, and bulkheads and have a "strong" hull.

Later,
Dan

[lamadriver]

Originally Posted by Matt Johnson

Monohull - but even with 2" of spray foam

I'd also recommend an EVA foam decking material instead of painted decks. We could always walk bare foot on the fiberglass boat, but any really sunny day required footware on deck of the AL boat. EVA foam would fix that too ... and add a bit of extra insulation below deck.

Matt

ive laid a material on my ally decks called TBS 21, its not a foam , but it has give and it not hard on feet , hands or knees and doesnt soak up the heat. No problem wwalkign on it in the tropics.

Ive thought about eva foam like Sea Deck. Talking to the guys who have it on race boats it gets replaced pretty often. I may use it on the interior.