Boxy Fisher Catamaran

Fanie, - Going well and looking good - - Congrats...

 

Fanie just as a wild guess what weight are you aiming for
complete boat before motors

why i am asking

including the pins it seems like you could end up close to half a ton for the 4 beams

BTW old Milton at Coplan Boats Walkerville says the prices of resin has come down, talking about some kind of a price war going on. i think he is buying Crayvalley, anyway well under R30/kg
You can phone him because i saved him BIG BUCKS on marine ply, he used to pay R500/sheet 9mm now from Schallies PTA R330/sheet 9mm

 

Hi Manie,

The parts are made to a certain strength. To achieve that strength I have to use a certain amount of glass. Since there are only two beams holding body and soul together I overdesign on them a bit.

The total weight without the cabin would thumb suck be around 2000kg, but it may go a bit over. How did you get to 500kg on the beams ? I could weigh them for you when they're done...

 

It seems like your beams are already at 60 to 70 kg each without ends and pins etc.
The 100 kg mark per each could come up very quikly, times four and the re-inforcing in the hulls for the beams and i would guess 500 kg could be possible

I had a look at the design concept as indicated in your 2 drawings and tried to visualize a couple of ways that such a hinge / beam arrangement could be made.
Please keep in mind that my experiences with "hinges" comes from mining which may or may not apply. The hinges that gave me **** in my life were on the buckets and arms of the CAT 950 loaders and on the articulation, that is the joint between the front and back wheels that makes it turn left or right. The other hinges that comes to mind were those on the massive vibrating shaker screens that we used to "sive" big stones from small stones.

What my concern is here are the huge loads that the hulls will impose on the beams and pivot points under wave action.
When you look at how strong a 16ft Hobycat beam structure is and the connection points on the hulls, you will see what my concern is.
As you are well aware there are many forces that act on a catamaran hull and beam structure and what has always worried me is how well resin performs under those loads when it was not moulded as one piece, the end pieces were added to the beams after the beams were fully cured. In other words wet resin on top of dry resin. The experiments that i did for you with epoxy on polyester wasn't that hot either and left a lot to be desired.

One thing that you should do is make up one complete beam and hinge arrangement and do a destructive test, this will be very difficult and probably expensive but your safety of the design rest entirely on those beams and hinges. The hulls on their own are unstable 10m long x 1.2m wide x 2?m high (for standing headroom for a big chap like you )

So my 2 cents, yes make it work for you, but get a 3rd party to do finite analises and sign it of, i would even go as far as saying that the average engineer that consults on his own is not good enough, go for the big boys in Rivonia that do mining engineering, they have a HUGE array of tools available

that hinge brakes in the Indian ocean you are shark food

 

Hi Manie,

Heinrich from MMS does my calculations for me. www.mmstechnology.co.za/ They are professional fiberglass designers and builders. I don't do anything before they haven't checked it for me.

The pins can do 120 tonns, the beams can do 40 tonns over a full beam. Heinrich did comment that I do not need such heavy beams, but I want them like that. I did also check the method of adhering the pins to the beams with them, the method is sound. I cannot show every detail on the drawing, it is only the principle you see there.

You also have to keep in mind that when you wrap glass around glass there is no chance of delamination.

Stick around. I will post pictures as I proceed. You'll see when I get there.

How can you campare this to a hoby cat good grief

As for the weight, how much does 10m catamarans weigh ?

 

jeez MMS sure looks good

must say probably better than rivonia oops

okay carry on

 

The peel ply came off, and just to please you Manie I added some more weight

Beacause the glass was wrapped there is shallow hollows between the layers. It could have been from wrapping the peel ply too tight. I just smoothened them up instead of down. Added about half a kilo there, but I'll sand about 100g off again

 

Fanie, ready to cruise (with full crew compliment), as light as possible - fill all voids with balloons of helium and seal... mine is 40 ft and less than 5000kg so yours at 30 ft 3000KG? as a rude guess??? (food fuel, eater everything)

 

Hi Mas,

I will rather judge too heavy than too light. I have it as between 201 kg's and 35000kg's, but I cannot tell for sure and exactly yet


Manie, that f paint

This is the first sign of a **** paint company. To get half - I kid you not - HALF the hardner out I had to break the tin open. I haven't seen such a **** design in a long time. It was quite messy and tacky.

Secondly, as I explained, these small holes does not get closed up with the paint I used a brush and brushed the holes to try and fill them up. When I got to the first surface again, this is what it looked like. The holes now became bubbles and I had to start over to try and close them. The holes are very small, they look like dots and are less than 1mm in dia.

The paint also runs as all plascon paints do. They did not disappoint with my expectations so far If this was 2k then there would not have been this problem at all.

As for the abrasive resistance I will test tomorrow when dry, I do not have any real hopes wrt this however.

Lastly the price. At > R 1000 per 5L this paint must really really be durable and super abrasive resistant. The boat, with the amount of coats you have to give to make it look like something, is going to cost me around 50k. Not worth it and not to mention the dead weight it would add the the boat.

2k. The automotive industry doesn't use it for nothing on millions of cars. You get it from Auto Paint Centre, Magda or Venessa 012 653 5450

I will probably sand the beam down again and repaint with 2k. I won't buy ANY plascon products ever again

 

This is a 2k hand painted surface. I used those white little foam rollers and this is 2 layers. The foam roller gives it that fine hammertone finish, it is smooth but not slippery. This surface finish will get even better if you give it a once over with fine water sandpaper (and water). Note, no bubbles

Also, I'm not big on maintenance, I don't want to repaint every year or three.

 

Fanie, I hope you were aware that my previous post was "tongue-in-cheek", but this is SERIOUS, Hi build bog, spatula spread and work in, let dry then sand, repeat process... those holes will NEVER seal by painting and will cause serious problems later by letting water in... With your epoxy mix, be very accurate and use a set of kitchen electronic scales that are reliable and ACCURATE... Mix your epoxy in those plastic container tubs that are used to serve Chinese rice/noodle meals... about 750mils capacity size... place empty on scale, zero, then add base, to desired weight, then hardener mix with a 2 ft long bit held in an CHEAP electric drill and mix fairly vigorously adding micro-spheres as necessary... If I am wrong (which I usually am) someone with hands on experience will counter post the correct procedure, like Judy of the http://scrumbleproject.wordpress.com/ ...

 

Hi Mas,

I'm not using epoxy But the holes and cavities were filled and smoothed.

The little tri was painted with 2k. Never had a problem. It was spray painted though.

 

Fanie is started this thread

http://www.boatdesign.net/forums/boat-building/paints-30185.html

i have read something similar a long time ago
this is not new and is definately the way i will go

btw my can (white) of the same as you got you can have as a present
see you on Friday

 

Thanks for the troubles Manie. I haven't had time to check the paint today, work set in. In good time...

 

This is my finding on the Plascon Glatex 8 paint -

It is now two days since the application of two layers. The paint is dry and it looks shiny. It is abrasive resistant in that even if you put sand paper to it it remains shiny.

I can however dig my thumb nail into it and scrape some pieces clean off. So it looks like the paint does not adhere to the fiberglass as well as I expected and for an epoxy paint I expected it to be much harder.

To apply a new coat on an old coat you will defenately have to sand the old surface down very well, I get the impression the second layer will delaminate very easy. I applied the second layer well before the first was dry and I get the impression that the two layers did not bond as well as one would expect.

Further the mentioning of it fading in sunlight and the eye watering price have me thinking I will deffenately pass on this paint.