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Post by jadcoz on Sept 17, 2013 10:49:17 GMT
Hello everyone , my first ever post ! I am buying a leader 805 boat for use on the coast of south of france , i will be using on the sea but also a lot on a small seawater lake called the Etang De Thau which is a wonderful lake , but heres my question - the lake itself is joined at either end by the canal du midi , enablng us to use the whole network of inland waterways which is what i have been used to hiring boats for the last few years heer, the sea is a whole new experience for me and i wanted to know would the 805 be ok trundling along at low speeds , say 4-5 knots for a few days , or would this damage the engine? of course as soon as i rech the lake again i can go back to normal 20 knots or so to clear engine but i really would love to know if prolonged use of engines at very slow speeds would damage anything?
Also what fuel economy would you expect me to get at these low speeds through canals? would it be a lot lower than normal cruising speed?
the boat i will buy will be the diesel engine i think
thank you so much if anyone can advise me - i simply cannot wait to get her moored up and ready to use in next couple of months
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Post by MalcolmP on Sept 18, 2013 14:35:00 GMT
Welcome to the forum and congratulations on the new boat. Regret I only have knowledge of a 39hp on a sailboat so rather different proposition, but hope that one of the Powerboat contributors may be able to share their experience with you
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Post by napoleon on Sept 29, 2013 9:24:52 GMT
Hello everyone , my first ever post ! I am buying a leader 805 boat for use on the coast of south of france , i will be using on the sea but also a lot on a small seawater lake called the Etang De Thau which is a wonderful lake , but heres my question - the lake itself is joined at either end by the canal du midi , enablng us to use the whole network of inland waterways which is what i have been used to hiring boats for the last few years heer, the sea is a whole new experience for me and i wanted to know would the 805 be ok trundling along at low speeds , say 4-5 knots for a few days , or would this damage the engine? of course as soon as i rech the lake again i can go back to normal 20 knots or so to clear engine but i really would love to know if prolonged use of engines at very slow speeds would damage anything? Also what fuel economy would you expect me to get at these low speeds through canals? would it be a lot lower than normal cruising speed? the boat i will buy will be the diesel engine i think thank you so much if anyone can advise me - i simply cannot wait to get her moored up and ready to use in next couple of months
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Post by napoleon on Sept 29, 2013 9:41:57 GMT
Running a diesel engine at slow speed for an extended period should have no ill effects at all subject to one proviso.
It is essential that the engine is properly run in before embarking on extended periods of constant speed either low or high. Many engines have had the cylinder bores polished with consequent high oil consumption as they have not been bedded in as is achieved with the normal running in process. If the engine is new then a progressive build-up of speed over several hours will help a lot. Constant speed over many hours will cause problems if not run in. When run in the engine will be happy to run for extended periods at low or high rpm.
My own boat (Jeanneau 36) is on the sea and is run for many hours at 1200rpm as this gives max displacement speed and a three fold reduction in consumption. In this case consumption is measured as mpg rather than amount per hour as the dynamics change once on the plane. Dropping the speed to 1000rpm gives a fourfold increase in mpg and only one knot reduction in speed.
When running at around 20 knots we arrive several times faster than at low rpm but with fuel consumption back to only a quarter of the mpg rate.
Hope this helps.
Napoleon
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