c class destroyer

[steven smith 6Participant @stevensmith6]

I am now well into the build, today I put the waterline on, and went to the lake, at 60 inches the hull is too big for the bath.

I felt that if I put the right weight into the hull, I'd get an idea of how to balance the weight through the ship

it took 4.5 Kg to get it to the waterline, that gives me 3Kg in the hull, and 1.5 Kg above the deck.

Now I need good suggestions for light motors, props and the like…….

I am going to use 1.5mm styrene for deck and superstructure, and very light brass angle for the signal mast.

[steven smith 6Participant @stevensmith6]

weighty problem

[Paul TParticipant @pault84577]

Steven

You could put the motors in a removable pod. With this you can employ heavier more powerful motors and fit the pod at the lake side, thus reducing the transport weight.

The removable motor pod becomes very effective ballast.

Its quite easy to do especially with spline UJs

Paul

[ashley needhamParticipant @ashleyneedham69188]

Steven. Not sure why you want light motors etc when there is so much ballast to be added!!

My HMS Manchester, at 57" runs on two Model Motors direct   555`s on 40mm 5 blade brass props and a  12v 7Ahr SLA battery very well. Ballast could be a few 4.5Ahr SLA batteries spread around.

Depends how fast you want to go really? assume 40ish mm props,  geared speed 400`s or 540`s would do?

Ashley

Edited By ashley needham on 17/10/2012 09:27:07

[steven smith 6Participant @stevensmith6]

The problem is freeboard.

The back of the Class has very little freeboard, so when tested to the waterline I have only 4.5Kg for the total weight of fittings in the ship, to take me to the waterline.

I have never built a C class before, so I'm going off what the old guys at the lake are telling me.

two thirds of the weight in the hull, 1 third for superstructure, 3 Kg hull, 1.5 Kg for the deck fittings.

Removable pods are ok but I still have the problem of weight in the water.

I'll post a pic of the c class hull.

[steven smith 6Participant @stevensmith6]

I have posted 4 photos showing the freeboard problem.

[Paul TParticipant @pault84577]

Steven

I understand (sorry I thought your problem was related to transport weight)

3kg is still quite a lot of ballast to bring the hull to its waterline and even after you have taken off the weight of standard machinery and batteries I would suspect that you will still need to add between 500>800g of extra weight.

At 1.5kg the upper works seem a little heavy to me.

I would suggest that you proceed with fitting out the hull with standard running gear (mfa motors or whatever you have to hand) and then reweigh the hull to see what tolerance you have left. Then build the complete superstructure and check that weight and check that weight against your allowable total.

Finally you will be able to trim the boat by buying the correct weight of batteries and distributing them around the hull.

You could short cut the process by asking suppliers for the weights of their products and doing some desk top calculations.

Sorry its so long winded.

Paul

[steven smith 6Participant @stevensmith6]

Thanks Paul

I,m doing the estimates this week, the superstructure, my guess is around 400 grammes, around 2.5Kg for the hull fittings, say 3Kg, that leaves 1.5Kg.

Every model maker I speak to has a different take on the weigh problem, so I'm just going to build it, so I will keep an eye on the weight, but what you have said makes sense, so I'll do it that way.

I will keep a photographic diary, and post pics from time to time

steve

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