Does anyone have a Monterey 250cr running a Yanmar 240 diesel ?

QBhoy said:
It’s surely got to be a 1.65 ratio I’d think. That’s what will likely show the most realistic prop slip figures, if I’m assuming some realistic performance and rpm data off the top of my head here. You think your tacho is accurate at 3800 rpm ? Is the spec rpm supposed to be less perhaps ? Early 3000’s ? So she’s definitely a bravo 1x diesel specific outdrive we think ? Does the outdrive say “diesel” on it ? Up the top of the outdrive on one of the decals, there will likely be a stamp saying “1.65r” or “1.50r” or similar. Any way to have a look ?
Although that bravo one propeller you have, can be a great prop on the right boat (for a 4 blade at least), I would be almost certainly confident to say that it wouldn’t have been fitted on that boat when new. Someone has likely added that prop to her at a later date. Could be wrong.
So from here. We really need to know some accurate numbers on gps speed top end and at what rpm. If the rpm spec for that engine is say 3300 rpm, it’s maybe unlikely it will allow you to actually achieve a figure of 3800rpm, by means of a governor or other means of interventio
QBhoy said:
It’s surely got to be a 1.65 ratio I’d think. That’s what will likely show the most realistic prop slip figures, if I’m assuming some realistic performance and rpm data off the top of my head here. You think your tacho is accurate at 3800 rpm ? Is the spec rpm supposed to be less perhaps ? Early 3000’s ? So she’s definitely a bravo 1x diesel specific outdrive we think ? Does the outdrive say “diesel” on it ? Up the top of the outdrive on one of the decals, there will likely be a stamp saying “1.65r” or “1.50r” or similar. Any way to have a look ?
Although that bravo one propeller you have, can be a great prop on the right boat (for a 4 blade at least), I would be almost certainly confident to say that it wouldn’t have been fitted on that boat when new. Someone has likely added that prop to her at a later date. Could be wrong.
So from here. We really need to know some accurate numbers on gps speed top end and at what rpm. If the rpm spec for that engine is say 3300 rpm, it’s maybe unlikely it will allow you to actually achieve a figure of 3800rpm, by means of a governor or other means of intervention and limitation.
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Thanks unfortunately there are no decals on the outdrive to check however you may be correct it being 1:65. ( is there another way of finding out ?) My plan is to take it out and run some tests at WOT and rpm checks against gps taco etc and build up some data to take a view. I was told by another forum member that he was working for the company that imported these boats which were originally built for petrol engines however they put diesel engines in and that the prop was the correct but doesn't mean its the right one.Anyhow will come back with some test results to discuss further. Thanks for your time
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SampoSam said:
I am now getting 20-22knots at 3800 true rpm -
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Ok. Something is way wrong then, I’d say. Have you checked the propeller hub kit ? To make sure it’s ok ? The hub insert that goes into the propeller is a sacrificial design that will give way if struck. It sometimes then slips under load, but holds on just enough to get you home. Or anything in between. I’d look there first. Or the coupler too.
 
QBhoy said:
Ok. Something is way wrong then, I’d say. Have you checked the propeller hub kit ? To make sure it’s ok ? The hub insert that goes into the propeller is a sacrificial design that will give way if struck. It sometimes then slips under load, but holds on just enough to get you home. Or anything in between. I’d look there first. Or the coupler too.
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originally that was a theory but was told that propeller doesn't have a hub kit or sacrificial design. plus i have tried 2 different propellers and didn't make any difference. Also the fact that after having all the work done on the engine we have increased speed from 9 knots to 22knots so better but still should be 27 - 30 knots. I am currently thinking i have too much weight on board ( now emptied water tank) and will remove all tools etc.. and see. if no joy then will try a separate fuel supply to see if that makes any difference
 
SampoSam said:
originally that was a theory but was told that propeller doesn't have a hub kit or sacrificial design. plus i have tried 2 different propellers and didn't make any difference. Also the fact that after having all the work done on the engine we have increased speed from 9 knots to 22knots so better but still should be 27 - 30 knots. I am currently thinking i have too much weight on board ( now emptied water tank) and will remove all tools etc.. and see. if no joy then will try a separate fuel supply to see if that makes any difference
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It almost certainly does, I’m sure. If it’s a bravo 4 blade from Mercury, then there should be a flo torq hub kit in it.
 
ok will check but the fact that all the engine and turbo refurb i had done has improved speed from 9 knots to 22 knots makes me think its not that but i will check again. Thanks
 
SampoSam said:
ok will check but the fact that all the engine and turbo refurb i had done has improved speed from 9 knots to 22 knots makes me think its not that but i will check again. Thanks
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Hi
So, I looked back through some messages between the previous owner of the boat I knew and I.
It was in fact a bravo 3 twin prop he had. Same engine though and perhaps the same ratio as you. It was a 1.65 diesel bravo 3. Maybe an X model. Can’t quite remember.
So he had 22” props and ran about 3300 into the early to mid 30 mph range.
This makes me perhaps think you may have an optimistic tachometer perhaps and in truth, have a much lower than indicated rpm. Meaning you are likely over propped (assuming a similar ratio) with that big heavy 24” 4 blade. I am almost positive that your boat wouldn’t have came supplied with that prop you have now. Not sure any boat would have, in truth.
Not to question you or doubt you…but if there is any ounce of doubt in your mind at all, around the tachometer…I would absolutely find a way of ensuring or reading the true rpm achieved.
Sorry again…but is there any chance at all that this engine and outdrive combo may not be original to the boat ? This may explain at least one or both of two things.
1. If she was a petrol v8 originally, the tacho may still be on the 8 cylinder setting on the back of the gauge. Might also explain the bravo one outdrive.
2. As well as the latter, a bravo one mated to a petrol or that may have came from a petrol (then fitted onto your boat), would have a fair chance of having a ratio outside what we are assuming here.
Anyway…some info for you at the least.
 
Hi sorry for delayed response been away on holidays.Thanks again for your continued interest. I have tested the tacho using a laser gun on the crank and seems that the tacho is showing around 300 rpm over at the upper end which makes sense.Another forum member confirmed that he had imported these boats and fitted them with diesel engines and the 24" 4 blade prop but didn't know the ratio.I am still waiting to test the boat with all weight out to see if that makes a difference but weather hasn't been kind recently. Will let you know asap.
 
does anyone know where i might be able to find a prop supplier in both east that i can test a 27 " prop for Bravo 1 4 blade ?
 
ChromeDome said:
It's all in the name. Mercruiser (inboard) and Mercury (outboard) shared many accessories and even made some for other makes. To support sales to non-Merc customers the more generic brand Quicksilver was used. I believe they tend to brand accessories aimed at Merc by their name now.

The benefit of PVS is that you can play with it and just put the plugs back in if not happy. If you (manage to) drill holes in your prop you won't have that option (drilling in these isn't easy!) unless you get it accurate and buy a set of OEM plugs
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no prop doest have a plug on it ?
 
Any idea where i can buy a new propeller can't find other than through US or eBay or amazon which rather not do ?
 
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