Weight at the ends?

[Jamestj]

In a reply to Nigel's "what servo do you use" , Peter said "you will still end up with a hull that is really too heavy in its ends"

I am trying to design an IOM and I had read that they can be twitchy to sail. I thought that it would be a good idea to reduce this effect by putting the electrical bits at the back. My reasoning being -

1) This will give the hull a bit of inertia so that it doesn't change direction so quickly

2) The expensive bits can be put all together under one hatch

3) The hatch will be clear of the boom so changing batteries and crystals would be easier, the switch will be more accessible.

4) A bit of weight at the back will help stop the pointed end diving under the water

5) The fin will be placed further forward to balance the boat so there will be more distance between the rudder and fin. This will allow a smaller rudder to have the same effect and the rudder will be further from the turbulence caused by the fin

6) Weight will be saved since the sterering servo will be beside the rudder and the winch drum will replace the transom block

7) The transom is a strong flat bit of wood designed to take the pull of the sails and seems a good place to mount heavy items

8 ) The transom should be out of the way of the spray caused by the hull skipping over the water as the boat takes the chequered flag (or whatever the nautical equivalent is.)

Clearly I have missed something out there since all the plans I have seen drawn up by experienced and successful racers put the weight in the middle.

Now I haven't actually sailed a model yacht yet and I don't intend to until I have a better idea how they work. However finding out is a great experience and draws on so many disciplines.

Oops - I forgot my question. Why is the weight put in the middle of an IOM?

Many thanks.

[edmorales]

In a reply to Nigel's "what servo do you use" , Peter said "you will still end up with a hull that is really too heavy in its ends"
Why is the weight put in the middle of an IOM?

Many thanks.

things such as center of bouyancy, gravity and center of lateral resistance i guess and to prevent hobby horsing
ed

[spaldi01]

Hi James

You have posted quite a few questions here which challenge current IOM practice. This is a good thing and if you believe strongly I would encourage you to try them. After all nothing ventured nothing gained. However:

Some may consider IOMs twitchy when pushed hard but you don’t want a boat that will not turn quickly when having a tacking duel with an opponent. So reducing the inertia to turning IMHO is a good thing (Some skippers are moving away from the long leads used on most IOMs to create a boat that will turn quickly.)

With a bit of ingenuity you can get all the RC bits under one hatch under the boom.

I also don’t believe that placing the RC equipment at the stern would reduce the tendency to nose dive. This is because the centre of gravity acts through one point which does not change (if the boat is going to float on its planned waterline.) So if you move the RC equipment back you have to move some other weight forward by an equal moment.

I agree with you about placing the servo near the rudder to reduce the length of the linkage, and I do this on my boats, but I do it to reduce linkage flex and I believe that a 30g servo does not increase the inertia very much.

Having the RC equipment near the centre of the boat makes it possible to place it below the waterline, which slightly increases the righting moment, which is a good thing. Placing the equipment at the stern doesn’t allow this.

Please feel free to challenge any of what I have written here and keep up the good work

Chris