Boxy Fisher Catamaran

[Fanie]

I've started a new thread on this one, the idea is to hold myself accountable to get some things done, as well as pic up some information, tips and so on from you guys. Be nice if you have comments or advice, so thanks in advance.

The boxy isn't going to be finished in a few months, rather in a few years. If you will be patient, so will I Our summer temperature is too hot and the resin gells too fast for such big structures, so any major glassing will be done in the winter months to gain time to work it properly. The time in between will be used to learn, desigh and prepare properly. Time and available funds is another thing to deal with. Sucks if the world buggers the economy up, but I'm not waiting another 5, 10, 40, 299 1/2 years for them to come right

Here is the intent - note not all ther details have been finalised

10m LOA x 7m BOA catamaran
Draft 400mm design for 500mm
Bridgedeck clearance 800mm
Sailing as well as motorized.
Two outboards, 40 to 60hp
Two 12m standalone aft masts
Sailing area roughly 45 to 50 sq m each
Standing headroom cabin
Standing headroom hulls
Daggerboards and kick up rudders
All controls can be done from within the cabin
Berthing 8 persons
Four port-a-potty's and four gass powered showers with a small basin each

Trailable, the two hulls will be interconnected with two hinged beams
When folded the two hulls will be 2m500 max to make trailable width
The beams are going to be about 400mm x 300mm to handle the forces
The pivots I have decided on will be HDPE, 120mm dia and can handle 33 tons

The cabin will ride on a second trailer. Details to get it on the hulls and off again has been worked out. There may be times one does not want to take the cabin, so planning is the boat must work with or without the cabin.

I haven't started glassing yet. The beams will be first in line because I want to make their housing they fold into that has to be an integated part in the hulls when the hulls are made.

I have to put up another building to build the hulls in.

Since the fiberglass is a third of the overall boat I have made a 'start building' by collecting and making some of the the seemingly endless list of accessories. No where near complete or enough, but I have a few thing to show in the meantime.

Not putting up any pictures yet, will show some of the items as I go along.

The hulls have been changed a bit, the draft came down from 500mm to 400mm for the same payload, but I'll keep the design draft at 500mm. More wiemen and beer

At this stage it all looks a bit overwhelming from where I stand, but the only way to eat an elephant is piece by piece

[Fanie]

Some boating activities going on here.

Since the post above, quite a bit has changed.

One of my friends just bought himseld two 12m pontoons for a pleasure boat. I'm off to see them tomorrom in the yard. Had a chat with him about all the crap going on here and aye made a decision. Lets see how she goes.

I'm ordering some resin tomorrow, the rep was here. Some brief discussion and it seems the receptionist giving me prices was struck by lightning when she did.

I've submitted drawings for the hull's roto jig to be quoted on. I should get the quote tomorrow. The jig is 11m long. This may turn out a usable item, my friend above got some ground from their council to develop, he has to build 5 house boats - the jig may well be used for that as well.

I know many of you probably gave up on the Boxy fisher catamaran, but the preparations, testing and everything else involved takes an unbelievable amount of time.

Once the preparations are done and the equipment works, it is supposed to take one day to assemble the jig. One day to glass the hull, when cured properly, one day to dismantle the jig, one day to re-assemble, and one day to glass the second hull, when cured, one day to disassemble again.

Keep in mind this will be done by myself and probably one or two other persons. Since I have to work in between, there may be a day or a week in between lapsing with no hard evidence appearing.

I'm going to start on the beams next.

[Richard Atkin]

good luck Fanie. I AM hoping the American economy implodes. In fact....it will. It's going to be a major depression. The timing is perfect for me. China will be the next empire.

Hey, it's your boat - nobody else's. Take all the time you need!

cheers

[Fanie]

I helped a friend this weekend with his 12m x 6m pleasure boat. It gave me an opportunity to get a feel for my own venture and if it is what I really want in terms of size.

The 10m is about right. Anything shorter will not suffice, 9m is going to be too short.

The width of 6 to 7m is also about right. Narrower will make the cabin cramped.

Only the hulls will be a bit narrow at 1m200. This is due to making the two hulls fit in beside one another on a trailer, max width 2m500.

[Fanie]

Next step is the beams. The resin arrived last week friday and the glass is on order. I have a few minor changes to make on the beam jig and I'll also get a chance to test the glass wetout machine then.

I've designed a clam cleat and sent for laser cutting. I'll assemble one when received and test it. If it works well I'll have some more laser cut.

I got a price for the roto jig's core, 11m long and 600mm dia. Loaded with 1000kg the calculated deflection is going to be about 8mm. The price however makes my eyes water...

[Fanie]

The drive for the roto jig is ready. When I get the jig I'll weld the drive sprocket to it and it will be able to rotate by itself.

There is a single phse to three phase converter driving a motor driving a gearbox driving the roto jig. The sprockets and chain I got for R10 at the scarap yard...The chain link cost me R20 new

The glass has not arrived yet, they promissed this week. I'll use the same drive to rotate the beams with when they get glassed.

The beams will be 300mm x 400mm ID and 10mm glass. This means they can carry around 40 000kg on the 4m600 length. I have also figgered a way to make the hinges. Will post pics when I do it.

[boat fan]

Fanie , can you put up a simple concept sketch of the boat ?

Just trying to picture it .....

[Fanie]

Sure.

Not to scale in the picture, but you should get the idea. The aft beam may hinge towards the rear, but this I will decide when the hulls are there. It will save space inside the hulls which is already narrow.

[Fanie]

The pivots I have decided on will be HDPE, 120mm dia and can handle 33 tons

The pivots or rather hinges will be fiberglass, pins already made. Their sheer strength is calcutated to carry 220 000kg each and they will fit in the beams vertically so the beams hinge action is horzontal.

The beams jig. I have to make four beams. When the glass has cured the pipe comes out, the jig colapses and the wood comes out to be assembled for the next beam.

[boat fan]

Thank you Fanie ...much clearer in my mind now ....

To manufacture those pins , the glass is " wound around the collapsible " jig " or mold , yes?

How is the glass saturated with resin ...to get a good resin / glass ratio ?.
Too much resin ...surplus weight , cost , weakness in laminate ....?
I find composites fascinating...
Those tubes do look strong !!

[Fanie]

The pins was wound like this - under tension. I'm the one on the right and my friend Philip on the left lends a hand. The glass resin ratio came in just below 2:1.

The jig was pulled from the pins using two trees

The contrapsion is a glass feeder where the glass will get feed through and between two squishing rollers to get the right glass resin ratio. I haven't tested it yet but will soon. There shouldn't be a reason it doesn't work. Target ratio is 2:1 glass resin.

[Fanie]

How is the glass saturated with resin ...to get a good resin / glass ratio ?.
Too much resin ...surplus weight , cost , weakness in laminate ....?
I find composites fascinating...
Those tubes do look strong !!

Glass was saturated with a wooly roller like when you paint. The tentioning squished the excess resin out, as I said I weighed the resin vs glass, it came in under 2 glass 1 resin. There is no weakness in the lamination, there cannot be, lives will depend on this.

The beams and it's parts will be made a bit of an overkill. Since our butts will depend on this I'm not taking any chances with it. It must be able to endure the worst...

[Ad Hoc]

Make sure your hinge, in the beams, can take the same vertical load as the pivots. Why are they hinged and also then pivoted at the inboard sides, rather than taken to the outboard side?..just curious

You also need to make sure the attachment points of the pivots, on the hull, can take the 220tonne you quoted.

Since the weak link in your beam arrangement is the hinge and the connection of the pivots to the hull. And then identifying the load paths available to shirk the load when applied.

[boat fan]

Yes , was wondering the same Fanie ,why pivot on inboard side of hulls ?


BTW, your glass winder and resin " mangle " look like they will do the job nicely
well done !!

[Fanie]

The boat is trailable, remember, if it sticks out too far to the rear it may cause some problems.

The way I do the parts etc is so that fortunately I can make changes yet. Sometimes in one's mind something will be best one way, but when you get there you find something else better or more desireable, then you can change it.