Can the BD 722 be supplied to fit the old Volvo Penta MD-2B footprint in my 31 Dufour? I'm confirming the measurements this weekend but my tech data shows the Volvo to be 205 MM laterally between centers on the stringers and I see the BD722 is showing 185. I'm not sure about the front to back measurements. Also, is the BD 722 powerful enough to obtain hull speed, with some reserve for adverse conditions, for this boat or should I go for more HP? I like the smaller size, light weight and lower cost of the 722. Thanks, bb
It is not a problem to supply the BD722 on 205mm mounts instead of 185. We have these mounts in stock.
As far as the engine size is concerned. When your boat was built, there was not the same choice of engine sizes available and the boat builders used what was either available or was cheapest. Volvo sizing went from 10HP to 23 to 36 and that was that. With that choice, Dufour made the correct decision. Now you are able to fine tune the engine to the boat and the Dufour 31 is only 9500lbs dry and has a very easily driven hull. I agree with your choice of the BD722 (Beta 20) as this engine with the correct propeller will drive your boat at hull speed with reserve. This same engine is used in much heavier boats such as the Pearson Vanguard with success.
Hi Stanley, Another question on the Dufour 31 repower. In measuring the lateral dimensions on the mounts, I noted that the Volvo Penta is tilted (higher in front - lower in back) on fabicated steel motor mounts in such that the propeller shaft exits at a mild angle. It makes me wonder if the original auxillary on this boat (I know it was replaced with a used replacement MD2B years ago) was the MD2B with the 7 degree down angle. The angle of approach on the shaft looks to be in the neighborhood of that angle. My question: Am I correct in assuming it would be better to mount the engine flat and match the down angle rather than "cocking" the engine in the compartment as I now have? If so, if memory serves, the old 70s vintage MD2Bs only came with one down angle (7 degrees), right? Thanks, bill
I think that you are correct. Your description certainly sounds like a modified mount and if this is so, I suggest that you fit an engine with a 7 degree down angle transmission. It is always easier to work with an engine that is mounted nearly level. When the beds are angled, you will have a lot more time invested in the labor part of your repower. We can supply the BD722 (Beta 20) with the Kanzaki 7degree down angle transmission. This is available with 2.33:1 or 2.64:1 forward ratios and is only slightly more expensive than the standard transmission on the small engines.
I can email a drawing of the BD722 with this transmission to your email address. I have just discovered when trying to attach the pdf to this reply, that this forum doesn't support pdf files.
Stanley, I checked the angle of the Volvo drive train and it's pretty close to 10 degreees, so it would seem the 7 degree down angle option is appropriate for me. Any suggestions on which transmission ratio I should select? Thanks, b
Thanks for the input Stanley. I I talked to Craig Pringle at McCauley Boatworks today and he's going to get in touch with you to order the BD 722. I need to update the raw water intake because the seacock is original to the boat and leaking a little. I also think it's too small. What size intake does the 722 require? Thanks, Bill
