Part 1. Ideal conditions; nearly 30°C, cool Bier at hand😜 Sea Scout built by Dad in the early sixties with a Taycol Target and 6V lead acid wet cells (very wet😡). Renovated and dragged into the 21st century over the last several months 😉 See Build Blog 'Sea Scout 'Jessica'' for details! Motor: Propdrive 2830, 1000kV, 30mm 3 blade Raboesch prop. Quicrun 16BL30 (30A) ESC with BEC. Tested with 3 battery types, all started with 99% measured capacity- 1. NiMh 4.2Ah 7.2V, nom. 408gm. Result: Speed sedate (OK 😉scale river cruising!) No planing. Max current: 3.6A End status V / capacity left: At end of short run ca 3 mins. 7.78V 99%. 2. 2S LiPo 4.0Ah 7.4V nom. 257gm. Result: Speed still sedate but due to lower batt weight at least the forefoot came out of the wet stuff! Max current: 4.1A End status V / capacity left: At end of short run ca 3 mins. 8.25V 93%. 3. 3S LiPo 4.0Ah 11.1V nom. 315gm. Result: Now we're getting somewhere!!😁 Good speed, manoeuvrability and planing 😊 Max current: 7.5A End status: 11.95V 74% after several long runs, ca 20 mins total. Estimated (extrapolated) endurance on a 4Ah LiPo around one hour - mostly 'full bore' - 'Pedal to the metal man' 😊 See also: https://youtu.be/oMUlSOaAREM The competition! https://youtu.be/zPgYicA0yGw Final run. (Beer was getting warm😁) Cap'ns log entry: Boat dead-weight w/o battery: 1.8kg. Spray rails to be added!😲 Slight list to port to be trimmed. Rudder servo to be reversed!!😲 Keel protection to be added: some scratches and flaking from stony sloping shore 🤔 Summary: much as expected👍 Forget anything less than 3S. Anyone want to buy a batch (4) of new 2S 4Ah 45C Lipos? 'One careful owner'! Happy boating people, Cheers Doug 😎 PS Many thanks to Camera girl Gisela 👍 Recorded in 1080p HD.
Looks like everything is set for the first open water test. Sun is shining, ice has gone and water smooth. Intention is to start the open water test program with a repeat of the pool test, except this time with everything wired correctly; the load cell positioned so the “pull” is more horizontal and ballast available to hold the propellers underwater if necessary. Hope these improvements help reading stability. To modify the “pull” arrangements, wrapped a light cord around the propeller shaft struts and fed the loose end above the transom shelf and out over the stern. The load cell was hooked into this and then tied to a fixed grating on the pond side. Started by measuring the electrical requirements for each of the three motors and the propeller bollard pull, using the 2 S battery. Found the bollard pull was up slightly at almost 3 lbs per propeller. Probably because they were now held at a greater depth in the water. Also blew several 20A fuses, so fitted 30, which seem to work. A series of runs showed adequate performance with plenty of spray, although the bow did not lift much onto the plane. The forefoot did raise almost above the water surface. Then tried a 3S battery. Although this was much heavier, the performance improved dramatically. The bollard pull was up to almost 18 lbs per shaft. The bow still did not lift much to a plane, although the forefoot was almost clear of the water at full speed. The battery was located just back from the bow, so it is suspected that it held the bow down. The impact of the transom flap down angle could also hold the bow down, but have decided to leave as is for the time being and avoid the temptation of making too many adjustment at once. Whilst it is still too early to draw definite conclusions, it seems as if a 3S battery will be required. The model sustained some slight damage due to the test arrangements, so will repair that and also fit the 2 bladed Hi Speed propellers. Will then repeat the program and report. Should be able to draw some definite conclusions then on the best power train. Neither of the batteries used, neither the 2 S nor the 3S are ones I would choose for this model. As a result the capacities and weights are not ideal. That must also be remembered in future deliberations.
Depending on what voltage you intend using governs what gearing you should use commensurate with size and weight of model and prop size , IE small boat and prop ,low voltage direct drive would do. As you go bigger then consider gearing.Bear in mind the torque produced by the drill. You could build a large boat with a fine turn of speed using that motor. The thing is there are so many possible variables you could experiment till the cows come home. The thing is how big a boat can you handle without putting your back out. LOL. If you remove the existing gear and replace it with one secured by grub screws and a "GearBox" with easily changed cogs you can achieve something suitable. You shouldn't need cooling .Remember the drill had none and your motor will have free space round it in the hull. If you decide you do want cooling annealed copper tubing can be wound round the can and one of the plastic tubes used to couple this to the scoop and the outlet. One way of making a scoop is a length of tubing with a slot cut in it and a cap soldered (or glued depending on material) on the end when in place under the hull the cutout will face forward. Preferably in the prop wash.Or buy a ready made scoop from a model shop. Much simpler as the mounting method will be incorporated in it already. Here is a page of suitable shops.--https://www.google.co.uk/search?q=model+boat+shops&npsic=0&r... Good luck. P.S. Join a club. Youll get loads of help from the other members.👍👍
Hi all, a 1/16th scale model of the boat I used to live on at Burnham-on-Crouch. 1/8th" Cuban (yes really!) mahogany from 1920s chairs made by my cabinet maker Grandfather. Covered in J cloth and epoxy. J-cloth is very compliant, but yet very strong when soaked in epoxy (WEST System). Lightweight fillered for the bits where the saw wasn't as accurate ripping the strips as it might have been. Black enamel primer.
Ill take some photos so people can see them, the old man would always show people them if they were interested. I did have a list of all the engines i came across it not so long ago as i didnt know what they were all called. He also told me a story years ago about having so much trouble with a 15cc taplin twin as he threw it over a fench in the 60's and started making his own engines, because he said it was rubbish and now on ebay they have a cult following. 😁 (Im not sure how true this was because he was a horder and didnt throw much away found the list includes the weight of each engine as i guess this was important when designing the boats!!) Stephen
Ah, cellulose, of blessed memory. I still have some, come to think of it, but forgetfully, I bought black gloss enamel for Vanity and some enamel primer for it also in black First coat on today. But I will definitely experiment with spraying the final coats. I sprayed an old pre-War Marblehead with enamel and it went on well. You can still get cellulose if you can convince the dealer it's for your classic car. My son has a 1951 Renown so I could always quote all IT'S details to get it, but I don't think they'll post it and I'm nowhere near any suppliers geographically. I couldn't see the point in paying for epoxy tissue so I bought a huge bag of J cloths from Poundland and used that with epoxy. Slarred the epoxy on the mahogany hull (made from old chair legs my Grandad had made a dining suite with) and then laid the J-cloth on the tacky epoxy and slarred more on with an old credit card. All my credit cards are old now and a damned site more useful as epoxy squeegees than they ever were before. Got a few ridges where they overlapped, but filler sorted that out. The hull is still very light, so will need all the large lead weights on the end of a long fin keel (removable) as it carries a big rig, (see avatar). Good luck, Martin
Talk about embarrassing, the little boat would not sail. The wind actually pushed the boat sideways into shore, absolutely no forward motion! I removed the added keel weights ( washers as seen in photos) Reduce the sail area, and still no forward motion, just sat in the water, looking pretty with slack sails. Pondering ???
I have brought the wiring home we with me. I will change the switch and take it back with me in August. I must admit that I thought the stern was a bit low in the water. To evenly distribute the weight, I put in two batteries as suggested. I will try to move the batteries forward to change the centre of gravity.😊
I agree with the weight being shifted forward a iittle bit.Bow high in a catamaran will catch too much air causing the boat to flip.All it takes is a good gust of wind.Good speed on the boat.After trials you'll have a good fast boat.
Hi Peter very unusual problem with the switch😲 You could temporarily replace it with a bullet connector to continue trials. Glue one end down so that you can quickly unplug the battery one handed. OR: simply short circuit the switch and use the fuse as the 'switch'!? Boat looks a little heavy / tail heavy? Maybe shift some weight a little forward to give more stability? Happy trialling, cheers Doug 😎
From the brief pool test, had decided that the motors could be susceptible to overheating, so connected up the water jacket cooling system and powered it with a small pump. Did not leave enough space to fit a scoop behind a propeller anyway, but prefer the positive action of a pump though. From feeling the ESCs, was also concerned they could overheat within a confined space such as the hull. Mounted a couple of small fans in a bridge structure above the ESCs, along with the ESC switches. Not sure either of these cooling modifications are really required, but erred on the side of caution. Final weight of the hull, with all electrics (apart from battery) comes to 5.05 lbs. Looks like will not achieve the target weight of 6 lbs, but am hopeful will be able to get close to it.. Built the deck up with gun mount bases and a removable decking over the engine area. This limits access to the internals; so will not fit it permanently until the test program is complete and all modifications incorporated. Have now reached a point where any further work will be to start finishing the model, unless drivetrain modifications are required. Have thus decided to leave it until after the first open water test date. This will be in late May as am away until then.
Hi Shaun, This design of hull forces the craft higher and higher the faster it goes. When it is high on the plane and almost hanging on the last few inches of propshaft it can fall off the plane either way, usually to the right (Starboard) side because of engine torque. The full size boats were fitted with 2 or 3 engines to help counteract this. The British Powerboat Company, who originally designed the hull that Vospers copied back in the 1930s/40s also noticed this which led to double skinning the hull with 1 inch thick mahogany for extra strength against pounding and falling on the waves. Lowering the drive angle of the propellor shafts and adding more weight from the C of G back to near the stern. We build this 3 screwed designed hull with one mainshaft usually so do not have the benefit of shaft rotation to stabilise the boat at speed. It was in the 1960's that Fairey engineers had the same problems (Swordsman,Huntsman etc) They came up with large transom mounted powered Trim Tabs. Their boats had similar problems and only one shaft in the main. I suggest you try fitting 2 x 2 inch wide by 1 inch deep trim tabs at the very bottom of your transom midway between the keel and the chine as well as move your battery packs forward a bit initially. Try some fast tests with this, you only need 2 to 4 degrees of down on the tabs initially. Add removeable weights near the CG as needed, a bit at a time but don't stop the bow lifting up onto the plane. Have fun, best of luck. Ron Rees
Whilst waiting for the ice to melt, decided to make up the deck and transom flaps. The deck was made from styrene sheet, again for lightness. Made the deck beams out of square styrene sections to avoid traditional, heavy, full width bulkheads. Hoped the stiff MTBH hull would resist twisting without bulkheads. First impressions are that this is the case and when the deck is finally bonded to the hull, should be even better.. The transom flap was made from thin aluminium plate and added simulated stiffener ribs in styrene. Understand that about a 2 degree flap down inclination works best on this model. My original plan was to operate the flap using a servo with another radio channel, however once the best plane is achieved it is unlikely the flaps will need further adjustment. Unlike the real vessel, the operating weight will remain fairly constant. So, abandoned the servo idea to use adjustable bottle-screws instead. The flap angle can still be adjusted, but not in motion. These screws are much simpler, lighter and cheaper than a servo. One challenge was to make the very small hinges required for an adjustable flap. After much thinking and investigation, decided the simplest and neatest way would be to use thin, self adhesive aluminium tape, as used on forced air heating ducts. Would stick the self adhesive surface to the underside of the flap and then onto the inside face of another thin aluminium sheet, which could then be fitted to the transom using double sided tape and small screws. This seems to work so far, it also avoids drilling through holes into the transom .