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Hi there, a good looking boat, well done. I also have an Imara which I am currently outfitting the motors (Caldercraft CEM 900T) and electrics, but need advice on the amount of ballast required to get it the correct waterline What was the total weight of the ballast you used? Many Thanks..........Richard
Well the measurements are close to the Siren, which is a USA design. Weight should be about 480 grams of which 200 grams are ballast. I use domestic scales but the kitchen may have a suitable type provided permission can be obtained. You could just rest the keel on the scales with the boat on its side to get an indication. The rudder is clearly a mod and may not be in the original designed position. On such a short length boat this may be relatively critical. Can you see if there are any marks on the hull suggesting a previous fitting? Are the sails the original that came with the model?
I agree with Dave, the hull etc is orange but the rudder is nicely finished wood with a blob of epoxy holding the rudder shaft???? also the keel weight has signs of blistering under the paint, has the weight been cut down???? The keel is not removable so the only way is to experiment by adding some extra weight, a couple of photos show a small hole in the balance weight, i wonder if the plug has been missing for some time and some of the lead shot has fallen out???? Dont know a lot about footies but an ounce of lead would make a critical difference Mark
Weight? Hmm how am I going get that? Take it to my butcher shop, maybe he will weigh it for me...as to length, width, height, I can do that now. Length of hull only: 12” Beam: 4 3/8” (113mm) Keel weight? It is not removable.
Photos are good. I don't like the look of that rudder. Looks like it is an original keel. I need to know the dimensions of the hull, overall weight and keel weight to compare with the models on the website, please
Ok Is the weight and dimension the same as the Siren or 507? Looking at the rudder this looks like an after fit and does seem to be differently mounted (more vertical) than those on the website. The keel looks flat on the bottom. Has it been chopped in half? This would make the model very sensitive, especially in a gust. I'll wait for your response before adding more thoughts.
Have had a look at the photo's, my thought is with Dave M, the mast is ahead of the keel balance, that is what is forcing the hull round under wind pressure, instead of a counterbalance, the bows are forced down bringing the keel weight even further back with the bows digging in even more. Did you build this model??? if so is there room in the hull to move the keel and its supports close up to the mast?? Mark
I am not familiar with this particular model, was it built from a kit, published plan? Adding lead to the keel will help to keep the boat upright in strong winds, but will add weight. I can understand the logic for your suggestion but really it's the keel support / mast position that looks wrong. Is the keel removable?
Mum went to the international model boat show and was amazed at the prices. She also thought they were rubbish for the money, her words not mine. She was a professional dress maker. So will update when there done, they take a couple of hours to Knit each one and the front fender all day. I think they look good, the small fenders are filled with a wine cork shanfered both ends on a lathe (thats the bit i do) to maintain the shape and a small weight added so they hang right. Note the cork means they will float if one gets bashed. Regards stephen.
Thanks Jarvo for the additional info...I did Google the safety bag afterwards actually. But...given what you've both advised.......as a stepwise approach, rather than discard x2motors plus ESCs plus batteries all at once, do you think perhaps upgrade the batteries first (more power less weight) and re-assess ? Then , if still not satisfactory, change the motors and Escs ? J
HI JJ. Your question about a safety bag, Damaged / overcharged lipo's can catch fire, think of the Boeing scandal that grounded the fleet last year. Charging in a safety bag is advised the bag is fire retardant material, which will contain any problem. Your remarks about the boat not coming onto the plane is down to the weight of the battery, my fireboat started with 7.2v NimH packs 1 for each motor, Graupner 700bb's, good cruise but not quick, but short run time, 10mins. I have re-wired to allow 3s lipo's, but not had chance to test it yet, but should go like stink. With a fast hull, weight is important, 4 x lipo packs, 1kg, half the weight and possibly 6 times the power delivery. In your first post you mention 600 motors on 6volts, they are probably rated at 8.4volts, same as my 700's hence the lack of performance, also the battery, at 12ah it should last about 30mins, was it fully charged??? and is it showing at least 6volts, ie not got a duff cell??? Canabus, in his post described an ideal set up with brushless motors, 1600 watts is just over 2 hp, 750 per horsepower so you can see the difference in performance with different motors and battery set up's
Hi What type of props are you using(size and number of blades). I see your basic problem is under powered motors and a very heavy battery. I made the big switch over three years ago from brush to brushless motors and to Lipo batteries. With the help on the forum and club members it was a learning curve, but, I would not go back. A 5800mah Lipo battery is in the weight of 450 to 570 grams and would give you a good 1/2 hour run time. A good balance charger and safety bag are the main requirements, also maximum charging for the 5800mah battery is 5.8 Amps(same as the old Nicads). Also a low voltage battery alarm. Your 600 motors can draw up to12Amps !!! Replacement same size motors for your mounts would be 35mm brushless motors, but, you will require two ESCs with a Y connector to run on the same throttle channel. Replacement brushless motors are far more powerful e.g. a Hobbyking 3639-1100kv with a 60Amp ESC on a 4S 5800mah Lipo Battery is 800watts and with two in your boat is 1600 watts!!! Your old motor would in the 100 watt each mark !! I have the same size crash tender, but, with a single brushless motor. I have all the order numbers for the motors etc. and a setup the ESCs if your require. Canabus
Only a short one, as I have realised that dealing with Battery Mounting means I need to deal with changing the Rudder Servo first! (Pic 1) So to remove the servo was easy as was replacing with the better unit. It is by the way much easier to remove the Servo Bracket and then the Servo than leaving it in. Same naturally applies when fitting (Pic 2/3) I had to remember to have the lead coming out on the correct side though! (Pic 4) I had been thinking about whether I should be using proper metal linkages to the rudder mechanism and issues about ‘slop’, but now it looks like there will not be a choice, but let us leave that until later as this is going to be a short session. (Pic 5) In fitting the battery I was conscious that it has to pass in and out of that rear hatch, stay on the centre line and avoid fouling the Rudder Servo...................... So I cut a base plate of Balsa to stick in the bottom of the Hull so making it reasonably flat for the Battery and a Balsa Plank to stop the Battery accidentally moving towards the gear boxes. Before gluing them in place I attached Velcro/ hook and eye patches to hold the Battery in place. (Pic 6 ) There appears to be at least two thicknesses of this stuff, very rigid and strong and the other softer, more flexible and slightly less ‘grab power’ (Pic 7 ). I opted for the lighter stuff as it could be a struggle getting in and out of the Hatch! (Pic 8) I may need to put a loop of something around the battery to assist in removal, but that is for later. I just glued the Balsa in with ‘Gorilla’ glue and laid the battery in to add weight whilst drying (Pic 9/10/11) Next time I hope to concentrate on getting the forward platform loaded and the power linked up. NPJ
Agreed Dave👍 A 10 cell NiMH would be my solution, or depending on type of boat; size, weight, performance demands, motor current etc possibly a 12V SLA or 2 x 6V SLA. I use the latter very happily in my 140cm destroyer and 100cm submarine and can tap off 6V for various low current ancillary functions. Will also do the same with my Graf Spee and Belfast refits - provides useful ballast as well 😉 Cheers Doug 😎
Great stuff Neil Good progress👍 You have come to some very similar conclusions as I have with my Southampton conversion! have just ordered NiMH drive and RX batteries as I realised that the P94 is not Lipo safe and has no BEC. So the BEC you mention for 'less critical items' would have to be an external SBEC or UBEC! Something else to find a corner for! Also I've long since junked my ancient NiMH drive packs anyway. I've also been considering changing the rudder servo, but not because I'm fiddling with the rudders, there's no point in wasting time with that as they will be motor assisted anyway. 😉 I simply have some smaller, but still powerful, ones to give more room for the battery. I was about to tell you to remove the heatsinks from the P94 when I read further down! I thought when I ordered them that 10 quid or so for a couple of chunks of alu ain't worth it when I've got sheets of it on the shelf😉 I also concluded that the only place for a decent drive battery is between the shafts; a) ya gotta be able to get it out for charging / exchange, b) I wanted to keep the extra weight nearer midships. Keep up the good work, cheers Doug 😎