Aluminum Catamaran Build

[Compactorguy]

Your material is going to cost twice what it would have two years ago 😵*💫

[Dr.No]

elsener 44, your Mumby design looks very nice. Your choice of materials is perfect, there is no question here that you have done your research. I agree with all the fore mentioned advice, especially that of Manateeman and Noelex 77 - there are very few members in this aluminum boat owners/boatbuilders club. Getting significant personal welding experience, as well as a professional welder initially, will get the project going properly. We use a Miller 350P dedicated aluminum welding machine. This model is in use with some of the PNW builders. For continuity, I have one guy that does all the welding, and if you PM me, I am happy to put you in contact with him. The specific settings on machine get tricky to figure out. The majority of Leeja’s hull is 6mm 5083. We use 5356 filler wire. One prebuild recommendation is to consider watertight bulkheads. We added two (additional) bulkheads at significant expense and trouble. It would have been far easier in the initial build. Freeman Marine in Oregon designed and built custom walk through watertight doors. Cheers!

[Manateeman]

Excellent and sound advice based on in depth experience.
The forum members are sincere and simply trying to help .
They have taken the time from their own projects to try to point you in the right direction. Please carefully consider that the breath and depth of their collective knowledge is an extremely valuable resource.
Happy 4th of July .
Captain Mark and the Manatee crew.

[Constellation49]

Elsener,

We are installing 3” of EPDM rubber on the inside of the hull. We also coated the inside of the hull with Mascoat which prevents condensation. These are installed every where except below the waterline.

[LargeMarge]

re -- 1/8" (or 4mm) hull
.
Garsh, that sounds awfully thin.
Is your 48 engineered for lake/bay racing exclusively?
.
For offshore, our monohull design uses 5/8" (16mm +/-) in the grounding areas for stability.
And we use a second, inner, hull of 1/8" with water-tight compartments for bouyancy in case the outer hull is breached.
.
Disclaimer:
We engineer for:
* an earthquake, plus
* a tsunami, plus
* a fire
* at midnight
* during The Storm Of The Century
* while inverted
* with a broken shoulder
* while repelling contagious rioters.
No rational individual would build to our requirements.
That would be just weird, right?

[Ballsnall]

Originally Posted by LargeMarge

re -- 1/8" (or 4mm) hull

1/8" is more like 3mm.
You might want to hall out and add another internal skin, just to be sure!

[mcarthur]

We have 12mm hull and 6mm superstructure, but build in a different manner to all others.

[Simi 60]

Originally Posted by LargeMarge

re -- 1/8" (or 4mm) hull
.
Garsh, that sounds awfully thin.
Is your 48 engineered for lake/bay racing exclusively?
.

Mumby and their variants have been running the world's oceans for 20 years now
Plenty of use in uncharted reef strewn areas
I think that says it all.

[elsener44]

Hello Everyone,
I know it's been a while and I really appreciate all your input.
I got started on the build with a professional alu boat builder in Port Townsend.
We are 3 moths and 1 week into the build and expect the hull to be finished in another 5 moths tops before getting into the outfit stage. I'm sure I'll have a few more questions for all you experts on here which is very much appreciated. You guys have really helped a lot in the different decision making and lots of helpful tips and ideas! I ended up getting the alu via Singapore for less than half of the price in the US including import.
I keep a little photo documentation for myself here if anyone wants to take a look: www.instagram.com/pioneeryachts
Here is the latest progress.
Happy holidays everyone.

[Dave_S]

Originally Posted by elsener44

Hello Everyone,
I know it's been a while and I really appreciate all your input.
I got started on the build with a professional alu boat builder in Port Townsend.
We are 3 moths and 1 week into the build and expect the hull to be finished in another 5 moths tops before getting into the outfit stage. I'm sure I'll have a few more questions for all you experts on here which is very much appreciated. You guys have really helped a lot in the different decision making and lots of helpful tips and ideas! I ended up getting the alu via Singapore for less than half of the price in the US including import.
I keep a little photo documentation for myself here if anyone wants to take a look: www.instagram.com/pioneeryachts
Here is the latest progress.
Happy holidays everyone.

It looks great 😃

Do you just hand form the sheets around the frames for the bottom of the hulls ?

Was it possible to get a complex curve with the 3mm?

Do you mind sharing your contact for the aluminium supplier in Singapore ?

Did you import it laser cut and pressed or on sheets ?

[elsener44]

Thank you!
Yes we hand roll the sheets with a roller we made ourselves. There is a video on our instagram that shows how we do it.
The bottom plates we roll are 4mm sheets, the 3mm sheets are only on the deck.
It was possible to get the complex compound curve. It took a little bit of customizing but you get the hang of it as you go and it gets easier.
We got the aluminum from Aerodynamic Metals in Singapore.
Here is the contact info:
The guys name is Zenco, great to deal with.
Aerodynamic Metals
1 Tuas Bay Close #03-02 West Wing,
Liner @ Tuas Singapore 636997
Tel: (65) 6558 8911 Fax: (65) 6558 8915
HP: (65) 9720 7434
Email: zenco@aerodynamicmetals.com
Website: Aerodynamic Metals Pte Ltd - Aluminium Alloy Supplier
Skype: sundartiwari
If you import into the US make sure you declare the plates as clad plated aluminum. It'll safe you a ton in dumping fees.
The sheets came in large plates and we used a local waterjet CNC cutting place to cut the bulkheads. Everything else we cut with a skill saw.
You can laser cut as well but it's more expensive and results are the same.
Cheers