Questions

I am planning to layup the foam using a single layer of 200g/sq m carbon cloth with a double layer in the centre of the hull from the chainplate area to the 1m for'ard of the front beam. Outside layer of carbon will be 0/90 in one layer ( the cloth is 1.5m wide ) and the inside layer will be -45deg/ +45 deg with a double layer in the centre of the hull from aft of the centreboard to for'ard of the front beam.

Is this enough?

I also plan to have a sheer clamp from Divinycell and cover is carbon fiber to help increase the gluing are when I glue the deck to the hull. An alternative is to use a timber sheer clamp instead. Any thoughts on this?

Thanks

Shane

Looking good Shane.

Can't help with your questions, but for chainplate location, what have you referenced this against? If taken from the Taipan, then this can be moved further aft. Taipan location was to allow the main to get out as far as possible, as people were sailing straight downwind at the time of design. We no longer do that, so can move chainplate aft and this takes some of the load off the chainplate due to the triangle to hold the mast has a large base. Boyer tried to get the Taipan class rules amended to allow this about 7 or 8 years ago.

This is what I have done on my homebuild Taipan F16. I've repositioned the side stay 200 mm further aft and I have never experienced any negative effects. Even when sailing without a spinnaker the boom never seems to go out far enough to touch it. The sail may however, up top, but you'll sail with some very large amount of twist when that happens. My sailing style doesn't seem to include this profile and it almost never happens with me. Note, that I do sail a numbers of times without the spinnaker, when I just want to sail around for an hour or so and not do all the rigging work. Just throwing up the mainsail and go like an A-cat works well for the short sailing trips.

Main point of this post is however that in my opinion TaipanFC has a good point. You can place the sidestays further back without any penalty. The benefits in lower stresses and a more tight forestay are significant though. Going from 500 mm to 700 mm is a large modification.

Best of luck building your boat !

Wouter

I was going to place the chainplate 68cm aft from the centre of the main cross beam which is the same as the Viper. Since I plan to use the Viper sailplan, mast and sidestays it would be easier to get the tuning done if I have the basic dimensions the same.

Shane

http://www.mcmc-uk.com/video/epoxy-foam.html

When you get to foils, this may help. Looks like a good way to build them. Especially to make them consistent.

Thread over at Sailing Anarchy about foil building, http://forums.sailinganarchy.com/index.php?showtopic=101093

Yes, I was talking to my composites supplier about the epoxy foam... trouble is I would have to make a female mold which is a bit troublesome. Unless I design the board to be used in a Taipan or Viper then I could have a sideline supplying boards to the Taipan or Viper fleet.

Retirement plan?

No, too early!

Any ideas on where to put the main beam? In the middle of the boat, slightly forward or slightly aft of middle? I think the Viper has it 2 inch forward of the middle but I gather that the current thinking is slightly aft of the middle so that you get more hull forward of that mast which helps if you want to push it harder downwind.

Any thoughts on this?

Shane

Applied the carbon fibre cloth yesterday. one piece of 200g/ sq m 2x2 carbon twill weave. Used too much epoxy because I didnt vacuum bag. Its just too big for one person to layup well... there are some bubbles which I have to fix.

[img:center]http://pics.livejournal.com/goodworks/pic/0000ayhh/[/img]

Shane, I'm sorry you're not getting much response to your thread. Why not try Mike Shappell at the "Man Shed"?

http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=199401#Post199401

I guess people are busy with family, christmas etc.
Really impressed with what you've done in such a short space of time though Shane. Amazing!

I look forward to seeing pics of the finished hulls (as, I'm sure, do you!! )

Pilgrim, A few tips,

Carbon on the outside is very vunerable to chafe and wear from beaching etc, put a layer or even two or 3 in the susceptable areas such as the bottom and trapezeing feet areas of glass. It won't add much weight as it has the benefit of mopping up the excess resin from the carbon layup.

I simply wet out the carbon and then place a layer of glass over the top, squeegee ( using a plastic filler applier )the glass into the carbon and you can soon see if you need more or less resin. I tend to layup a heavy glass cloth and then a very fine layer as this tends to flatten out the twill and therefore you need less filler and paint. Enevitably when you are fairing the outside before painting you can rub through the glass but it is obvious where as the carbon is not and much easier to repair.

In relation to the beam, it really depends on whether you are intending to be a single hander or double. If single then you can place the beam way back as per the A Class but with a two hander it becomes impractical as you need to be able to get the crew through under the sail, Bitsa is a bit extreme and even single handed it is tight. There are other benefits to having the beams back such as you need less volume up front and in theory should be a better light air performer without sacrificing Spinny down wind safety. Again Bitsa seems really difficult to bury the front as the Spinny clew is only about 1 metre ahead of the front of the hull even with max length pole.

The rear beam is much more tricky as it is really dependant on your rudder system and how long the arms of the rudder connection bar is. The system I used of gantrying out the rudders is too time consuming and I'm not sure that practical. Stick with the conventional I would say.
Fire the questions off as I'm sure there will be an answer.

Hi Wayne,
I do have a band of carbon cloth 100mm wide the length of the bottom and I plan to cover the whole hull with lightweight glass cloth. I have to get rid of some bubbles first... will cut an X shaped incision with my Dremel cutoff disc, fill with epoxy and put them back with a carbon cloth patch over it. Next time I will do the cloth in parts instead of one big 5m x 1.5m piece for the whole hull - I was too ambitious for a solo effort.

I do like the way your rudders are out back so you have good leverage on the tiller arms. I've been thinking how to do that with carbon rods and I might do something similiar.

Shane

Shane, using carbon as you intend can cause more problems than solve, a 100mm additional band without other layers transfering the load to the single layer, will cause such a hard edge between the layers that it will almost certainly crack the inner layer of the two. Always use carbon for stiffening and glass to transfer the loads + act as wear layer.

Everyone seems to think Carbon is the great thing to use, it very often is the wrong material and should be used with caution. An all carbon boat will weigh marginally less ( probably only 3 -4 kilos to a well built glass boat ( and how many of us are not 3 -4 kilos over weight ), cost 3 times more than glass, most certainly will be far less duriable and twice as hard to repair when you ding it.

It is christmas time.. I think I am +5 kilos just from christmas with the family so I certainly dont worry about carbon

From the picture it is hard to say what is bubbles, what is distortion in the cloth and what is bubbles. I really liked the plants and the bamboo in the pic though as we have about 100cm of snow the last week.
Putting on the cloth in one piece is OK if you organize the work. Ie starting at the middle and working outwards to both sides with one batch of 100grams epoxy at the time. Kayak and canoe builders do it all the time. A slow hardener might be better if you find the epoxy kicking too fast.


You are working fast, hope to get an on the water report soon.

Wayne,

any hope for a followup on how your snuffer works and more pics?

Wayne,

Thanks for your input. I will have a glass layer over everything for wear resistance. I dont think carbon is that bad. In aviation , models and full size, there is ample use of carbon in staggered multiple layers that allow taper in skin thickness without hard spots and stress concentrations to develop.
I also thought about the placement of the main beam and decided to place it 5 cm aft of the center. I will keep the rear beam 2m aft of the main beam like the Viper which leaves me 40cm between the rear beam and the transom. Thats a bit short so I will have to engineer a gantry like the Bitsa.

Rolf,
The cloth was distorted in places when I was draping it dry over foam. I smoothed it with a wide brush after draping. I applied the epoxy working from the middle to the ends. I use a 24 hr cure epoxy so I had enough time but it was very tiring because of the sheer area of the hull. When I applied the epoxy with the plastic spackle knife over the cloth I noticed that parts I worked on before had 2-3 cm air bubbles that just kept on returning even after I smoothed them down repeatedly with the spackle knife. The curved hull bottom was not affected and only the vertical sides.Next time I will cover the hull in parts and vacuum bag the cloth to the foam.

Even with a flash coat of epoxy applied to the foam beforehand, I used much more epoxy than I expected. The cloth was not shiny after application so I dont think I flooded the cloth so it must be that the Divinycell soaked up the resin like a sponge. I am anxious to weigh the hull...


Shane

You might have closed the pores in the foam with thickened epoxy (epoxy+microballons) mixed to a slurry and applied before placing the glass. (20/20 hindsight is not difficult, especially not while behind the keyboard).
I dont have much experience in glassing foam parts without vacuum. With wood it is imperative to not glass while the temperature is rising. Outgassing from wood is a problem. I dont know if divinycell is similar. What I do know is that the more you work the cloth after epoxy is applied, the harder it becomes to do a good job. Pushing air into the cloth.
When applying cloth over large pieces, I find it best to roll it on really carefully. Cloth that have been folded is never 100%, neither is cloth that have had any kind of force applied to it as it stretches and wrinkles so easily.
If I can choose, I prefer to put on the glass in a horizontal position. I find it much easier to get a good result if gravity helps me. Draping/applying epoxy to the "bottom" of the part first will distort the cloth when you come to the "flat" hull side.
You probably know all this from your RC building. I am just throwing out information that might be useful for others reading the forum.

Did you weight the resin and cloth before applying? If you do, you can track your progress while applying the cloth.

I think you are doing well. Keep up your efforts and you will be sailing soon. We have spent 1.5 years on our strip plank boats..

I primed the foam with clean epoxy ie no filler... that might be my problem. Next time I will use epoxy + microballoons... It really soaks like a sponge. I used about 3kg of epoxy for 1.5kg of cloth ( 7.5 sq m x 200g ). I dont think the cloth was oversoaked because it had a matt appearance. I think the epoxy went in to the foam.

I have to keep up the momentum otherwise I will lose interest and that will be a disaster.

Shane

I would have sealed the foam as suggested.. a micro-balloon mix.. sanded smooth and then applied the cloth. Foam eats epoxy!!


good luck

Happy New Year to all!

Figured out why I got the buubles under the cloth.

I started out by pouring epoxy from the top middle and worked my way to the ends. It was working great at first but as I worked to the ends, the action of pulling the resin down at the ends pushed the cloth towards the middle and caused the cloth to bunch up and buckle creating bubbles.

so to summarise the mistakes I made so far...

Mistake 1 - Used clean epoxy to prime the foam, should have used epoxy mixed with microballoons or Q cell.

Mistake 2 - Allowed the cloth to bunch up in the middle when applying epoxy at the ends during layup. Should either have used vacuum bagging or should have worked the spackle knife sideways towards the ends instead of top down.

Shane