IOMICA Forum

I am trying to find a little weight saving potential in my boat as it is about 210g over the limit.

I can save about 130g on the battery. In addition I have also been looking into a miniature servo. I am using a Futaba 9205 which weighs about 50g and looking at some of the smaller servos I could save up to 30g here.

What torque should the rudder servo have without giving up to much performance?

Look at some of the new digital servos from JR. They are smaller, lighter, and have more torque than most standard size analog models. A bit expensive but if you must lose that weight.....

210 sounds a lot overweight - which even if you do get a lighter servo and battery, you are presumably reducing weight in the centre of the boat which is exactly where you want to have any excess - you will still end up with a hull that is really too heavy in its ends - maybe you would be better spending your money on getting a new hull

cheers

peter

210 grams. that is equal to the weight of 210 cc of water and that is a lot

Well, 210, minus the 130 you say you can save with a battery change an a slighly smaller rudder servo, another 30 grams, leaves you with just 50 gram over weight.

This does not seem to warrent getting another hull to me, at my financial involvement in the hobby. The distribution of weight is probably not optimum (all central and down low, none in the ends or at deck level) but 0.8% overweight does not seem to warrent a new hull.

As for batteries, there are now 800 mah AAA size NiMH batteries available and the lithium ion batteries are quite light and have a capacity of about 1200 mah (as last I recall). That is the first place I would start.

Then, if you want to go to the extremes, you might want two keels, one less than the 2500 gm limit (by enought to bring you down to the 4 kg target an another at the 2500 gm limit for regattas with the heavier air conditions. Seems to be real overkill, with only 50 grams to worry about.

Lastly, are you using the extremely light arrow shafts for your booms? They come in various diameters and wall thicknesses and by selecting the right one, you might be able to shave a few grams here.
Ralph

I have gotten away from using the arrow shafts for jib booms after breaking 3 or 4. The Sails Etc. aluminum extrusions are much stronger (even after multiple holes are drilled in it for fittings etc.) and not much heavier.

Well Peter I think a new boat would be a little drastic measure too take, as the boat is very fast as soon as the wind picks up.

I ve just ordered a Hitec HS85 BB which only ways 22g and puts out 3,5kg torque.. and I also getting some AAA NiMh batteries.l This means I am looking at about 4050g total weight which I think is acceptable.

I have both jib and main for all 3 rigs on Easton X7 arrow shafts. These are the highest grade alloy Easton provides and are stiffer than the arrows that Sailsetc offers as light weight boom. I have not had a boom fail in 2 years.

Cheers

hi there nigel - what is the hull design and was it home made or bought - glad to hear its fast in blow

I tend to use GBs large square section booms on all 3 rigs simply cos I like to be able to lock the sheeting eyes, swivel points etc in place so they cant slip or move (but can easily alter their position if required just with a screwdriver or alan key) - plus I get a bit more sail area downwind (theoretically)

My boat is a German design called INSIDER. I bought it ready to sail, having had it completted by the chap that makes my sails. So it is sort of semi home made