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redviking

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  1. Steve, Have you had a chance to weigh the vessel yet? You may then be able to apply Crouch's formula to determine the approximate vessel speed. Did you use plywood thicknesses as per the original Aitken's design. If you are only using a 20 Hp engine with a 2:1 knockdown gearbox, this may be your issue.
  2. John, I forgot to answer the last couple of questions. 5) try a duramax or pss seal as I previuosly pointed out. The are designed for this application. 6) don't consider a oil bath white metal bearing. Do expensive and just not for this application. Try to get hold of any books by Dave Gerr or Ted Brewer about props, shafts, engines, systems, boat design etc. I have a couple at home which are good basic reference books for the amateur. They are written in a style that is easily understood. Try Amazon or book depot. Will set you back less than $20 per volume. They are well worth the investment. Best of luck with your project. I look forward to seeing the progress on this forum. Eric (Brisbane, Australia)
  3. John, I have been following Aitkins' Rescue Minor for a while with great interest. I am looking to build one myself in the not to distant future. I can give you some answers to your questions. Hopefully you can get some other contributions as well to improve the discussion and help you make some decision. 1) A cutlass bearing is forced water cooled and can be used on the waterline. I live in Australia and use an American brand called Duramax. The bearing will need to be force feed from the raw water overboard that comes out of the heat exchanger of the engine before going over the side 2)The bearing is open at the propeller end and sealed at the gearbox end. Use a Duramax or PSS seal at the inboard end. If you search the internet for either Duramax or PSS you willl easily find them. Both are companies based in the US and will have distributors all over. 3)Your old vessel probably did not have a keel as such and the shaft went through the hull and needed to be supported near the propeller hence the strut. Since the "Rescue Minor" has a keel, the bearing is mounted in the keel. No need to put any sought of fitted on the keel. 4)The means of changing direction of the shaft that Robb White mentions is great if you want to save a few quid (sorry bucks) and like to be seen to be a bit innovative. However if you can afford it buy a small gearbox to mount on the back of the engine. I am not familiar with the engine you are going to install, but if you talk with the supplier and tell him what you propose to do he will be able to help you out. These guys can be a fountain of knowledge as that is what they do, match engines to boats. With regards to the shaft bearings, depending on the length of the "shaft log" in the keel you will only need one bearing. An idea that I have seen used is to glue a stainless steel tube into the shaft log and mount the bearing inside the tube. That way when you need to change the bearing, simply knock out the bearing. Also the seal and be fitted to the end of the tube on the inside. The distance that the shaft will protude from the back of the bearing before the front of the propeller boss is 1". A rule of thumb is the diameter of the shaft is the amount that the shaft will protrude. Hope this helps. I am a Marine Engineer by trade and currently oversee large aluminium ferry rebuilds. Eric
  4. Steve, Have you had a chance to calculate/weigh the boat to determine the lightship displacement? I would be keen to know to work out some tech specs for engine sizing. Eric
  5. Steve, What was the rpm achieved by the engine when the vessel was operating at full speed? Is the 3800 rpm the design no load max rpm? Eric
  6. Steve, I was reading William Atkins original spec for the boat and noticed the engine sizing etc. I am interested to know why you chose a 2:1 reduction gearbox. Atkins uses a straight through drive (1:1) 2000 rpm, 25 HP. Even though his prop was 10 x 12, he suggest a top speed of 15 - 16 knots. Have you been able to determine if the engine is able to achieve 3000 rpm at full throttle? Great to see the boat on the water. Give the rest of us inspiration to get a move on with our own projects. Eric from Oz
  7. Steve, The photos really do Wally and yourself's hardwork justice. Do you have any performance stats as yet from your short trail? Did the engine perform as expected? You have no doubt inspired a new generation of Rescue Minor builders. Congrats on your success. Eric
  8. Steve, Great to see the progress you have made in such a short time. This is going to be the most looked at Rescur Minor built in a long time. I have a question which should have been asked when you were fitting the engine. How did you correctly drill the sterntube bore through the deadwood to ensure that the shaft alignment was correct? Eric
  9. I am looking at the plans of the Selwyn Fisher Thames 20 and am really impressed with the fine lines and the classic look. Has anyone looked at these plans/or built one at all to give me some idea about the degree of difficulty in building this boat and any tricks discovered while building Eric
  10. Steve, I know this is your forum, but, Karl, Would you be able to post some information and photos on your half model, as I am interested in building one with the tumblehome at the stern and a raked transom similar to a vintage Cruise Craft. Eric
  11. Steve, I live in Brisbane, Queensland. As the ad over here says beautiful one day perfect the next. I was reading through William Aitkens original spec for this boat calling for an engine doing 2000 rpm and a 10 x 12 in prop. Is the Westerbeke capable of doing in excess of 2000 rpm at top speed, or was that the only box available with this model? Eric
  12. Steve, Does this engine come with a gearbox as standard and if so what is the model and ratio. I am replying from Australia and have been following this construction with great interest. Eric
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