Hi Gary,
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Lets rewind the repower story and begin a new.
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Your boat is 14000 pounds or 7 tons, the design for auxillary is 3 hp/ton, this will get you along on calm days in relatively flat water. We have done many repowers over the years and have learned that a ratio of?3.5 hp/ton in most cases will get you hull speed.
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The BCC a grand old boat, but she is heavy, not a UDBL design sled.
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With that said, any horse power beyond what you need to reach hull speed is wasted along with the addition cost of a larger engine.?Most of the newer engine designs, in particular Westerbeke/Universal do not overload when you reach hull speed, they simply stop producing power, you can still push the throttle further forward, but you will gain nothing in return, gone is the black smoke telltail of yesteryears when you have overloaded the engine, it’s a process of new injection system technology.
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We proved this point last fall with the 35D THREE, where the customer speified a 1:1 ratio transmission for his Islander, when we reached hull speed at 2100 rpms, you could watch the throttle lever and injection pump control lever move beyond 2100 rpms, but no additional power, rpms or smoke-designed to be a clean burning engine.
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Imagine that, an engine that knows it limits.
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Over the years we have found the best horsepower/weight ratio is 3.5 hp/ton, this should take you to hull speed, handle adverse wind, wave?and current conditions.
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Your BCC is rated at 14,000 pounds or 7 tons, 7 x 3.5 hp =24.5 hp
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I know this is a lot less horsepower than you think you realy need, but hull speed is hull speed and there is no getting around it.
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I recommend you go with the Universal M25XPB, it’s a little shorter and narrower than the 35D Three, but it is a workhorse and there is a lot of them out there, they have been around for a long time, it’s one engine that is realy hard to kill, trust me, I have a lot of customers who tried (not by choice, you know, dumb stuff). Being a alot of them out there in boats means parts supplies will be around for a long time. In fact, it’s the hotest selliing engine in the Universal product line.
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The M25XPB is rated at 26 hp at 3000 rpm, 600 less than the 35D, it’s lighter as well, less is better. Down load the drawings from Westerbeke.com, max engine spacing is 16" and minimum is 11.5, this should get the job done, as well as, save you money.
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Since I have already saved you a grand on your repower, we expect you to buy a round of drinks at the next cruise-out, cheers.
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Best wishes,
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Marty Chin
Bay Marine Diesel
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Gary Mynett wrote:
Hi Marty:
I am emailing you directly because I know you are familiar with BCCs and
Westerbeke engines. As you may recall from my posting on the BCC board, I
am repowering my BCC (hull #064). It currently has a Volvo MD7-B and I am
hoping to replace it with a Westerbeke 35D.
The problem I am running into relates to the engine mount spacing. The
Westerbeke 35D has mounts 14.6" wide athwartships. The rear engine mounts
are just under 14" aft of the forward engine mounts. The result is that all
3 engine mounts fit into the available space with the exception of the aft
starboard mount.
The aft starboard mount runs into the curve of the hull. I was surprised to
learn that the reason for this is that, according to Sumio, the hull is not
symmetrical, such that the aft port mount does not encounter the curve of
the hull whereas the aft starboard mount does.
On my Volvo, the fore-aft spacing of the engine mounts is 9.25", so it
presents no problem. Do you have any experience with repowering BCCs? Other
engines I’ve looked at, including the Yanmar, present the same problem for
me (but are even worse).
My mechanic thinks it should be possible to modify the engine mount so that
it will fit.
I would appreciate any comments you can make.
Gary Mynett