Composite (glass/foam/glass) For Beginners?

I have no real experience so I can't really say, but here's what I would keep in mind:

You already have significant investment and progress with the CM method. This is sunk cost, and you probably won't get much if anything out of it if you sell. Go ahead and look for a better build method, one that would be "perfect" for you. Then compare that to what it would take to finish your current build, not to a complete new CM build.

By all means re-evaluate, but recognize your current progress. Write off what you have spent so far, that is gone, but acknowledge your assets. That's the way to make an honest decision on which direction to go.

Seems to me that you could hire some day labor and finish your current hulls for about the same as getting set up for a new method, but that's just a hunch. At least drive by home depot and see what the going rate is these days. Or put an add on craigslist. I'm sure there are a lot of guys on unemployement looking for cash jobs.

 

The quick answer is: I've spent $6000 on the CM build that would be thrown away. The rest of the $25K or so was spent on materials, tools and resources that would work well with the foam building process. So... $6000 is the difference.

However, I have one bad CM hull panel that will cost me a fortune to fix anyway. That's the one with the ripped bag that I need to cut up and put in the dumpster. Then, I have to do a new one, hiring people to lay it up and bag it. It takes a 4 man team.

So... my plan is to buy a boat, or build in a way I can build myself (mostly).

After looking at the garbage catamarans on the market in the $250K range, building is looking a lot more attractive again. It's amazing that 1/4 of a million dollars can't buy a decent catamaran (for my purposes of chartering, but that will also sail well).

 

Just a brainfarth:

Have you considered buying a Fusion 40 DIY package? (approx 140k USD)

www.cruisingnorth.com.au/

Or a Oceanic 373

www.rmkmarine.com.au

 

Yes, I had considered these as well as the Bob Oram Duflex boats. The problem with all of these kits is that (to my knowledge) they don't really get you that far ahead for the extra cost.

You get a hull, yes. However, you still have the full fit out to do. If you spend $140K + shipping ($10K) for just the hull parts, then still have to buy tons of biaxial tape, epoxy and all of that, I can't see that you are very far ahead of just making up your own panel on a vacuum bagging table.

Of course, I could be wrong, but I am not seeing how this is economically an advantage. Also the parts are enormous. How are they moving them around? They don't show that part in the link for the Fusion 40. Magically, the parts are all in place without anyone lifting them. They also appear to have to hire a 4 man crew.

I would rather do a kit, yes... but the prices are outrageous for what you end up with. I think the Bob Oram 44C is probably the easiest building technique for the price, but you still have a $10K shipping charge to the States, plus import duties, Australian taxes, etc. The materials cost to get the Kurt Hughes boat to the same stage as the Fusion or Oram are about $60K, but it takes a lot longer.

I don't know... what do you make of it?

To me, they don't seem worth the price and the pieces seem too big (except the small Duflex strips in the Bob Oram kit).

 

Anyway, I agree with that.. Now, this is just a calc figured while writing this, comparing to strip planked cat. 2km of 2" x 5" for strips, couple of board saws, two barrels epoxy and about the same amount of BIAX.. lets say 10k for the timber 7k for epox and 3k for fibers lets throw in 2k for fillers and 5k for occasional tools sanders etc we are about 27k.. I say it's quite good even if it's twice that compared to that 140k..

 

Concur!

In Europe the boat with a wood epoxy structure is seen as the higher value than a foam glass one. In fact almost all the world sees it so, just in the US wood epoxy is much underestimated and underrated.

Catbuilder
I cannot understand any reason why one man would build such Hughes boat. For a small team ok.
That is the most idiotic way for a homebuild one off, I could magine.
There is no shiny side with this method, neither in nor out. One would always have to handle panels the size of a tennis court. What a mad idea to offer such crap to a homebuilder.
And all the tooling! A full size table for bagging flat panels!
Completely insane..............

Go for a common strip planked hull (either foam or light timber)*. Build upside down on a strongback, as usual. That is easily done by one man, and you only need to turn each hull once.
I have no idea about existing designs, because I don´t like cats, as you know, but there must be many out there for strip building.
Even this design could be done in strips (or panels). The foam does not know if the panel is just 2m long or 15m. But this would sure need more temporary frames to support the foam. Means some lofting.

Regards
Richard
*and don´t let you talk into the "foam is better" nonsense! It is NOT. And it is not even lighter in almost all cases. And never in case of a homebuild.
see this for example:http://www.boatdesign.net/forums/ma...e-groove-strip-planking-624-3.html#post291246

 

Thanks for the advice.

I'm not sure why this designer likes to have such large pieces either. I would imagine you are correct that the foam planking originally described by Herman would work just as well here.

 

If you take a look at the PDF here:

http://www.dianeselkirk.com/PDFs/DIY Vacuum Bagging Basics.pdf

What do you think about the bagging equipment listed at the very bottom, rightmost part of this article on the last page?

I used a Shop Vac (wet/dry vacuum cleaner for the shop) and polyethylene sheeting last time. I sealed the edges with Liquid Nails. It actually worked very well, except when the crew holed the bag in an inaccessible spot. You couldn't even begin to lift the bag off the panel by grabbing a crease and pulling.

What products should I use for this one off boat's bagging?

 

http://www.airtechonline.com/

 

too slow my connection for dl the pdf file.
But a shop vac is for cleaning the mess it produces when abused for bagging!

Get a decent, but proper pump instead. Ebay is your friend........

The reason for the one panel (each side) design is most likely the additional stiffness the tortured ply gets when the stuff is hammered together. And sure he did not change the shape for foam construction.
But when there is a full set of sections in the drawings, you have all you need for foam or wood strip planking. (again, the wood can be the better choice and even lighter, especially when you can get Kiri - Paulownia tomentosa)

Regards
Richard

 

Thanks for the link to Airtech. They seem to have everything you need.

I was just looking at eBay for a vacuum pump and most all of them seemed to be a variation on the vacuum pump I currently have sitting around from HVAC work, which is this one:


RobinAir 3CFM - 40 Microns - 0.04 Torr or MM of Mercury - .532Mbar

Why is this pump bad, and which pump should I get for this?

Another question: How much more expensive is resin infusion than regular bagging? It looks like a good way to go when making flat panels on a table.

 

Because that pump is a toy Look 15 - 20 CFM is a base line, My shop pumps were 100 CFM and better for doing large work, Infusion! the setup and disposables add to the cost a little over straight wet bagging,like the feed system and get a electronic "Ear" to check for leaks as you will need 27 HG Minimum across the bag before opening the resin line.

 

Now I understand... that makes perfect sense. Thank you!

 

It is easy to get into trouble with a small pump, micro leaks along the bags perimeter especially over fiberglass are cumulative and quickly overtake the pump.

the other thing is air leaks sometimes are in the 30K range well out of our hearing, some of the leak detectors are heterodyne and a usable frequency is output,They are cheap and well worth the investment.

 

CatBuilder; your pump is big enough to do the infusion jobs of your size, not the ideal pump for just bagging parts as its best not to exceed 80% vacuum for this and these pumps are designed to run at full vacuum.
Main advantage of infusion is the quality, minimal exposure to resin and you can do very large parts on your own in one hit. Down side is extra cost, takes longer and potential for things going wrong increases.
As far as the bag film is concerned of course you get what you pay for, airtech and Aerovac films are much tougher than 100 micron hdpe but the later is what I mostly use. Econolon is a good compromise.

Search infusion, vacuum pumps, vacuum bagging on BD as there has been some good information on these topics in the past few years.
If you decide to go ahead I can provide more information.

As others have mentioned building a one off in foam is more expensive and one of the slowest ways to build a boat but in Australia people are willing to pay a premium for this especially in catamarans.
My preference for a compound curved one off foam construction is full half hull construction in a female batten mold with transverse planking of the topsides and only longitudional strips in the tight turn of the bilge.
These half hulls you will be able to maneouvre on your own much more easily than the moulded plywood ones as they are very stiff as you preinstall all the bulkheads to lock in the shape before you remove from the mould. You will need 4 chain blocks hanging from rafters or timber a frames to do this.

For catamarans 45+ feet in length then the look of flat topsides is not so much an issue and infused full length top sides will save time in building them and greatly reduce the external fairing time. The table for this does not have to be perfect edge gluing 1' 8 x 4 malamine covered MDF boards will do the job, I can get these that were used as cover sheets for $20 from my local plywood supplier.

Think this through carefully as I think you are greatly underestimating the time it takes to build a one off 46' cat especially in foam and reconsider finishing what you started or just buy the best boat you can find and accept that its not exactly what you want.

I think the kit boats are worth their money especially the Bob Oram boats as they are the kind of boat you are after, but even these in this size will take around 4500 hrs to complete to a good standard of finish.

Cheers
Andrew