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Calling Keefer Douglas

terry_thatcher

Terence Thatcher
Keefer, have you further adjusted your prop size? If so, how did it affect the cavitation noise and boat performance? Any other thoughts about the Beta 43? Did you have to rebuild the engine beds to install it? Looks like sort of a tight fit. And what kind of reduction/reverse gear are you running? Thanks.
 
Hi Terry,

We had the 18/12 prop that was originally installed with the Beta cut down to a 17/12.5, with no noticeable difference in cavitation (still quite noisy). We decided to just live with the noise this season. Will likely replace it with a 16/13 this winter, which Beta thinks is as small as we should go with the 43. Fingers crossed that fixes it. I am told the increased pitch will increase prop walk. But it is manageable with the 12.5, so I am not too worried.

Our installer added two aluminum rails to the sides of the engine bed and then mounted the Beta on top of those. I think the original fiberglass beds were a little too wide apart for the Beta mounts. There is plenty of room in the space for the engine, even with new 1" sound insulation on both sides and the ceiling. That said, I doubt you could go with a larger case alternator without some more serious reconfiguration. We have the 120 amp alternator offered as an option.

We have the TMC 60 transmission with 2:1 reduction.
 
Thanks very much. I ctually find prop walk helpful in close maneuvering. 120 amp alternator is plenty. My current Balmar is 100 amp. Do you have a Balmar or some other brand?
 
Beta uses Iskra alternators. Interestingly, they wire it assuming a single battery bank, with the positive pole on the alternator wired back through the starter motor. On my previous boat, as well as previously with the Perkins, I had followed Nigel Calder's advice (perhaps now already outdated?) to create a completely separate circuit for the starter battery, only connected to charging sources via an echo charger. Rather than mess with Beta's wiring, this time around I have gone with a single main bank for both house and cranking loads, with a separate "emergency" battery kept topped up via an echo charger while operating under normal conditions.

I had them install the brush kit to bypass the internal regulator on the Iskra alternator, and now use a Balmar MC-614 for regulation. Prior to that change, it was a bit disconcerting to have charging pegged at 14.2 volts for as long as the engine was running. I know people must have done that regularly without frying their batteries in the old days before we had good monitoring and multi-stage charging. And I get (from the good folks at Attainable Adventure) that even the Balmar and most other "smart" chargers aren't actually monitoring current acceptance via a shunt, mostly just running a timed program to cycle through bulk, absorption and float stages. But still I feel better having at least some control over the process and peace of mind if we need to motor for a long time with already charged batteries (which is often, since our primary modus operandi is weekend cruising the often calm Chesapeake in summer, with a boat that sits plugged in at the slip most of the time).
 
I have used the Balmar controllers for years. If I can figure out where to put a shunt, I may install a Wakespeed this winter, altho the Balmar has always seemed to do what I need. In the tropics the reduction in charging when the alternator and battery temps went up was especially valuable. If you don't have one, get a Balmar battery monitor--very valuable and simple to install. I have my alternator wired directly to one of my house batteries and use Blue Sea charging relays to connect the other house bank and the starter battery when charging, either from the engine or the solar panels.
 
Keefer, I forgot to ask. How high can you run your Beta 43 without cavitation and what speed do you get? If you get 6 knots without cavitation, that is pretty good cruising speed, and close to much efficient hull speed for the 382 (when not heeled to extend the working lwl) .
 
Unfortunately, cavitation starts early and gets louder with increased rpm. It is noticable by 1500 rpm, and at that point we are still under 6 kts. We still have our old 16/11 prop from the Perkins, going to have the shop try to bend that up to 16/13 and see where that gets us. Will report back again in the spring.
 
This cavitation issue is strange. Given the similarity between the hp and torque of the Perkins and Beta, I have to believe it is the prop diameter interacting with the small aperture.
Good luck.
 
We finally left the slip today for a quick test run. The prop noise is much reduced with the 16" diameter, but not gone entirely. My suspicion now is that there was always a little bit of noise, but it was less noticeable with the louder Perkins than the nice quiet Beta.

The 16/13 3-blade fixed prop that we have on there now also seems better suited to the Morgan + Beta 43 + 2:1 reduction gear combo. We were seeing 6.3 knots at 2200 RPM going straight into about a 10 knot breeze, and about 6.5 knots in the same conditions downwind. So the smaller prop needs a little closer to the ideal cruising RPM to get to hull speed.
 
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