R/C near scale yacht
|461 forum posts|
Son-in-law 'beemed down' a few photos of the maiden voyage. He was rather over-focused on catching me in my budget waders to begin with and then there was suddenly other things to 'focus' on due to the power failure on bord.
The propwash from my grandson's DJI drone (and the drone) can be seen in one of the photos so should have som video of the whole show in due course hopwfully with less 'green wellies'.
The yacht floats a bit nose down which is partly due to my having chosen the two foremost boltholes for keel fastening. I may have to locate and drill out the aft holes and move the keel aft. I have always felt that yacht would float 'stern-low'. Looks like it'll be a week before the weather here settles again so back to the yard for adjustments.
|461 forum posts|
The planning cell has been working during the night. It is assumed that the low Rx battery warning and shut-down has indeed been caused by the array of heavy-ish winch-servos. (Graupner 5217) struggling via BEC. The spring tensioners/ compensators in the hull are only stretched at one end of travel for each servo and at any particular time only one servo is at the 'stretching end' of travel. The servos don't sound strained at the end-travel point so I don't think this is a problem although some extra amps are needed to stretch the spring. End travel (and thus, spring stretch) has never-the-less now been reduced a little on all three servos. The Rx is now supplied by two identical 4.8v 2000mAh batts in parallel -which were in fact bought a year ago in case the BEC couldn't cope!
Longditudinal balance and the ugly-bug keel:-
From the few photos I have so far, I note a slight nose down attitude which needs to be corrected. A plan has been made to move the keel attatctment point a little further aft. Thanks to positive inputs on the forum, a new keel arrangement has been drawn up which it is hoped will cause less turbulence both under water and on the forum . The new keel will still not be an object of aesthethic beauty. I don't think I have ever seen an 'aesthetic' add-on keel -apart from the wing keel on Comtesse.
Buying new, even longer keel legs on Tuesday when shops open after Easter.
Edited By gecon on 04/04/2021 10:34:59
|461 forum posts|
Produced sail covers for the main and mizzen today. A bit oversize but I do not want to 'squeeze' the sails too much for fear of creasing the luff tape. The covers are probably large enough to use as storm sails.
Not too sure what to do about weighting down the stern yet. Moving the wing keel aft will help, but there is a limit to how far I dare move it. I may have to add weight into the aft bilges but this will just be on the waterline and not give significant added righting moment - just weight.
|Chris Fellows||05/04/2021 17:21:09|
985 forum posts
Would having a "keel fin" angled back make any difference or does it act from the mounting points?
|Eddie Lancaster||05/04/2021 17:22:29|
|843 forum posts|
She looks good George, and lovely setting to sail in.
|Tim Rowe||05/04/2021 18:09:52|
564 forum posts
Having the fin angled back would help. It acts through the centre of gravity of the combined fin and weight. The weight would have to be dropped at the aft end by the same angle. The advantage is that it does not increase the displacement and shifting weight is efficient as it lightens one end by the same amount it makes the other end heavy.
It would also change the centre of lateral resistance but I doubt that is a very critical feature of this arrangement.
|461 forum posts|
Hi all, I did in fact consider having an angle on the legs, but did not think that only getting an average of the aft movement of 'Longditudinal' CofG was good enough.
I have ordered new, longer legs which I will place further aft. Maybe I can even angle these slightly aft from the new attatchment point and get a bit more aft movement of L-CofG. So I'll acheive more depth + aft movement of weight.
Tim, the wing-keel ballast weight is not fastened as far aft as possible in relation to the fins. I could squeeze 10-15mm more if I cut+filed+faired here and there. So I will keep it in mind for the 'MkII' .
I thought that I might try to have the two legs (fins) join just below the hull to become one single, double-thicknes leg -or fin. I will need some good luck in 'bending at angles' to 'mirror-bend' the two legs accurately though! Could maybe ask a local car-body repair garage for help.
I do have a large bench vice but I'm not sure I can bend the 2mm galvanised legs as needed....I'l have a go though!
The first thing I need to do is estimate the required aftward weight-shift. The canoe stern of the Fisher does not provide much bouyancy compared with amidships so I may not need too much weight to move the L-CofG . I'll have to get back to a lake when the snow eases off and just add weights into the cockpit until the desired effect is acheived. At least I'll get an idea of the required weight-shift. At worst I'll need a bit more iron shot in the aft bilges as well. At at very, very worst...I'll re-paint the the line of the 'anti-fouling'!
Starting today by buying in the new legs and drawing up the required contraption-construction
Many thanks to all for inputs.
Edited By gecon on 06/04/2021 06:20:14
|461 forum posts|
Showing the 'old' keel and the new planned keel. Will not spend time painting the new one until floatation tests are completed. Maybe even leave it galvanised and silvery!
The new keel will be raked like there's no tomorrow -about 60* to the horizontal I suspect. Any less will not give enough weight transfer. Though I do not yet know how much weight I need to transfer.
Will start sawing-and-bending tomorrow. Will talk to a car bodywork mechanic if I can't bend the bits as required with the tools I have.
Edited By gecon on 06/04/2021 19:13:48
|Ray Wood 2||07/04/2021 10:56:29|
2418 forum posts
Lovely job she has turned out to be and looks great Can you use the roller reefing on the Genoa to take some power out of the rig ??
Just thought do you really need that contraption bolted on as extra righting moment ?? Your next boat the Colin Archer is similar in size and sails ok without the false add on keel, the hull can obviously support the ballast internally if there were room ?? Just a thought
|461 forum posts|
Hi Ray, I expect that the roller furling system could be used to reduce geonoa area. It would need to rolled in quite tightly to reduce the diameter of the rolled-in sailcloth. Although I would only need to roll in 50%. With it completely rolled in and with the sail covers on, I think it would even sail in a breeze. It will be a long time before I dare test it in much wind I suspect!
The Colin Archer needs about 6kg in the keel for sailing. I think I only manged to get about 3-3.5kg into the Fisher keel...much less than I expected in fact. I have indeed thought of the CA as a comparison and to avoid making the Fisher even heavier (now 10kg) I think the danglig contraption is needed.
The wing itself is only 1kg including the legs so it has to be placed well below the waterline in order to have any effect. I know that Fishers roll quite liberally and to begin with I don't want this one to ROLL too much. I can always unbolt the keel later if it's not needed.
I've been working on the new raked legs today and will do tests as soon as the weather let's up a bit.
Edited By gecon on 07/04/2021 18:11:52
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