30-40cm carbon fibre hull

[sundog]

Well I ran the other day with an inrunner motor and it seemed a little more controlled if nothing else! I didnt get any footage unfortunately as my only camera is my iPhone and I didnt fancy juggling it with this thing while trying to keep it under control!

What I found was that it would jump out of the water very frequently, giving poor control and not allowing you to really open it up. I moved the battery as far forward as possible, but it ended up just submarining, which caused water to get in and ruin my lovely £5.50 ESC - sadface!

I dont understand how the flexishafts work and what parts i need to implement one into my boat. My understanding is that you have a strut on the transom which holds a solid shaft with some bearings or bushes in and the flexishaft connects to this somehow? I dont understand how the shaft tube connects to this though and how leaking is prevented at the transom.

Cheers!

I think the problem is with the stuffing tube (strut) being so long, and exiting the hull so low in the transom that when the boat planes and gets up on the bottom blade of the prop, the boat is completely out of the water at that point. If you were to have the shaft exit the hull higher on the transom, it would settle down at speed. But finding that exact location might be elusive. That's where a strut comes in.

[minigazz]

I think you may be right there! I have tried shortening the stuffing tube and have tried to reduce the angle between the shaft and the bottom plane of the hull. I have also experimented with a wire drive. It still wont settle though! It porpoises terribly and flips over sometimes. Could it be the hull design or is it still workable?

[minigazz]

Also, with a flex shaft, does the flex shaft have to be held in a tube all the way from the motor/shaft coupling to the stringer drive?

[sundog]

Also, with a flex shaft, does the flex shaft have to be held in a tube all the way from the motor/shaft coupling to the stringer drive?

That is customary. But you could try just moving the shaft up in the transom to get the hull to come down some. In other words, drill another hole above where it is now and try it again. Can you take a picture of the side of the boat showing the transom and prop shaft. From that I can give you a good idea of where to drill the hole. Try to get a level, flat shot from the side. (see crappy drawing)

[minigazz]

I dont have access to a camera right now, however it is currently as low as it will possibly go (approx 1.5mm of the very bottom of the hull). I also noticed that the motor and speedo got very hot today, and the speedo strated playing up (its only a cheepy one off ebay from hong kong), but the props i use are about as small as i can get hold of for a 4mm threaded shaft and the motor is only 3000kv @ 11.1v?

[minigazz]

I am now in a position to start the design work on my new hull as I finally have some free time! I am pretty sure I am going to go for a mono and given the high price of carbon fibre I think I am going to use fibreglass initially.

When it comes to moulding the hull I assume i am going to have to make the hull in two parts - an upper and a lower part. I do not however want this join to be visible from the outside of the hull - this means no lips around the edge. I don't know if this is possible though to get a good enough join?

I also have no idea whether to go for a plug/mould constructed using balsa/ply planking over a ribbed frame of just to carve the hull plug from a solid piece of wood, i.e. mahogany?

Finally (for now, lol) I was wondering if anyone could recommend me a power setup for a fibreglass hull of approx 40cm in length. In the past I have used ebay motors and very cheap ebay escs (which seem to work well for around 15mins then die!)

Thanks

[aahwhatever2]

[minigazz]

Hi, would anyone know if it is worth me adding steps to hull this design? I have decided on a length of 38cm as it seems a good compromise between portability and stability. If it is worth doing, are there any rules to follow? Im hoping to finish the plans for the plug tomorrow so i can start the exciting stuff!

[minigazz]

I have now started my build blog here http://forums.offshoreelectrics.com/...bon-mono-build