Mahe 36: Sail Drives and Props

[Cotemar]

Colemj,

I agree with you and Scott730 about installing a separate thruhull for the engine intake and cap off the saildrive intake.
It's a very good idea, but no one has done it on a Mahe that I know off.

I do not have a problem where I am, so no need.

I think that most owners are just afraid to drill two more holes in their boat.

[tpkas]

Hello All,

I've scoured the website but am unable to find the standard prop size supplied ex factory with the D1-20 engine ... can anyone help me here? I have to replace my props as they've become badly pitted and if they are 16" x 11" (as I suspect) I'm thinking of going up to 16" x 13" . I'm not near the boat at the moment (in fact it's at Noosa having a new bottom applied - perhaps more on this soon in a different thread) so I can't measure anything or try to see part numbers. Also if anyone has a similar size prop (2 bladed fixed type) I'd be interested to hear of the performance they get. The reason I think it's an 11" pitch is that when I do the maths I should get 6kts at about 2200RPM and that seems to be reflected in the actual boat performance. An online prop calculator suggests a 13" pitch and for the same RPM it would mean an increase of speed at 2200RPM to 7kts ... and still not stressing the engine at all ....now wouldn't that be nice!

So, standard prop size is ....anyone?

Regards,

Brian

[Scott730]

Brian
You are correct, they are 16x11. Had to replace one of mine for the same reason. I kept the old one and filled the pitted areas with JB weld and sanded it smooth, will keep it as a spare. I asked Volvo about going with something like what you are thing of, 16x13 but they would not support it. Would like to know if you do go with the 16x13 and what kind of proformance you get.

Scott

[tpkas]

Thanks Scott,

can you recall why Volvo wouldn't support the higher pitch prop? I plan on calling the shipwright doing the repairs tomorrow and will ask for his opinion and may make a phone call to the Volvo support line to canvass their opinion as well. Will report my findings to the forum.

Regards,

Brian

[Scott730]

All I could get out of the Volvo rep was it was non standard and they only would support the standard configuration. Typical BS from a rep that didn't want to do any leg work or think outside the box. Since only one of my props needed replacement, I didn't push the issue. Think I paid around $200 US for the replacement. Volvo Part number 850342.
Scott

[MKB53]

Hi Brian

I replaced my standard props with feathering 3 bladed 15x13 props. These were the size recommended by the manufacturer based on the data I supplied. Their view was also that the pitch on the standard was low. I did not bother talking to the Volvo rep, they are not going to warranty anything after a year or two anyway.

I found the 3 blade 15x13 very good a bit faster and more traction.

The feathering props are expensive but a huge improvement of the fixed props when under sail. I happen to think they are better value for money than the Volvo folding props (at the price I was given) but I guess we all have our own view.
Cheers
Martin

[tpkas]

Hi Martin,

thanks you for your info. The folding props are out of my price range at the moment so it's between the 11" or 13" pitch fixed 2 blade props. Since we easily achieve max rpm with the 11" I've been advised that there shouldn't be a problem with the 13". Another source said we'd lose about 500rpm from the top end which, if my maths is correct, will still deliver the same top speed but means we'll achieve my desired cruising speed at lower rpm. As long as it doesn't stress the engine things should be fine ... of course we'll never know until I try. At this stage I think I'll give the higher pitch a go ... are engine rebuilds expensive?

.... Well, just while composing this I've received a call from the Volvo rep. He also thinks we'd lose 4-500rpm off the top. His recommendation is to stay with the standard 11". His advice was also to give the engines a good run at max rpm every now and to not be afraid of sitting them at higher rpm for extended times. The FP rep, while not discouraging experimentation with the 13" prop, also indicated that the reason the boat comes with 11" props is because FP have probably done their homework and think the 11" props are the better choice too ....

So there you have it .... I'll stick with the 11" pitch and not try to re-invent the wheel.


Regards,

Brian

[Clipperton]

Originally Posted by MKB53

Hi Brian

I replaced my standard props with feathering 3 bladed 15x13 props. These were the size recommended by the manufacturer based on the data I supplied. Their view was also that the pitch on the standard was low. I did not bother talking to the Volvo rep, they are not going to warranty anything after a year or two anyway.

I found the 3 blade 15x13 very good a bit faster and more traction.

The feathering props are expensive but a huge improvement of the fixed props when under sail. I happen to think they are better value for money than the Volvo folding props (at the price I was given) but I guess we all have our own view.
Cheers
Martin

Hello,
I am as well going to replace the fixed blades next year by feathering blades. I am thinking about the kiwi props or the maxprop. Which model did you buy?
Which cruising speed are you achieving at which rpm? (assuming that you have the 20 or the 30 hp)
Feathering are much better than folding when going reverse.
Alex

[DotDun]

Originally Posted by tpkas

Hi Martin,

thanks you for your info. The folding props are out of my price range at the moment so it's between the 11" or 13" pitch fixed 2 blade props. Since we easily achieve max rpm with the 11" I've been advised that there shouldn't be a problem with the 13". Another source said we'd lose about 500rpm from the top end which, if my maths is correct, will still deliver the same top speed but means we'll achieve my desired cruising speed at lower rpm. As long as it doesn't stress the engine things should be fine ... of course we'll never know until I try. At this stage I think I'll give the higher pitch a go ... are engine rebuilds expensive?

.... Well, just while composing this I've received a call from the Volvo rep. He also thinks we'd lose 4-500rpm off the top. His recommendation is to stay with the standard 11". His advice was also to give the engines a good run at max rpm every now and to not be afraid of sitting them at higher rpm for extended times. The FP rep, while not discouraging experimentation with the 13" prop, also indicated that the reason the boat comes with 11" props is because FP have probably done their homework and think the 11" props are the better choice too ....

So there you have it .... I'll stick with the 11" pitch and not try to re-invent the wheel.


Regards,

Brian

Any decent prop shop can re-pitch the 11 to a 12. Probably charge $20 to do so.

[MKB53]

Hi Alex

I looked at the Kiwi Prop but did not like it. I also read a couple of not very flattering reports on the net. I have no knowledge of Max Prop at all but have seen some good reports.

I bought the SeaHawk Autostream after reading some reports and discussion with the manufacturers. I have been very happy with it over the last 4 years and have done a bit over 800 hrs on them. Good traction astern as you suggest.
They look a bit "agricultural" but don't let that put you off.
They feather easily and have never "unfeathered" while sailing.

I have not taken specific rev/speed data as that was not the most important thing for me. Sailing performance is significantly better, especially in lighter air and you seem to tack easier as well. I normally run between 2500 and 2700 revs and in flat water will be doing a little over 7kts.

I also looked at Hydralign which looked good and were a visually better shape.

I did not get them because :
a: I liked the idea of Stainless steel Autostream,
b: They were more expensive than Autostream
c:the agents were not very helpful at all. If you don't get good support before you have bought it what happens afterwards?
d: The Autostream pitch is adjustable without disassembling the prop (ie: while in the water). I have never had to change it though.

Cheers
Martin

[Clipperton]

I checked on the net and I see what you mean regarding the Autostream look ;-)
The hydralign looks really like the max prop.
Nevertheless, both Autostream and hydralign seems like they are only distributed in Australia.

I would need to g to a boat show anyway to see all that for real.

Do you have link regrading the kiwi prop reviews?

Alx

[MKB53]

An update on the autostream performance. In ideal flat water conditions including a new antifoul she does 6.5 at 2300 revs and 7.4 at 2700 revs.

[jglauds]

Thanks for that ... out of curiosity, what size sail drives do you have? That seems like a very high RPM ... I'm used to pushing my D-30s at 2000-2200 rpm as a working maximum ... too conservative?

/jon

[MKB53]

Volvo D1-20s. They max out at 2800-3000 according to the manual. Mine go to 3000 but you don't go any faster and just burn diesel. The cruising revs recommendation was 300-400 revs less than max. Long distance I normally set it at 2500.

[Jacana]

Originally Posted by Cotemar

Colemj,

I agree with you and Scott730 about installing a separate thruhull for the engine intake and cap off the saildrive intake.
It's a very good idea, but no one has done it on a Mahe that I know off.

I do not have a problem where I am, so no need.

I think that most owners are just afraid to drill two more holes in their boat.

Have had 1 engine running too hot so beached the boat and cleaned out intake and still have about 50% less water coming out of intake ,will install a trial seawater tank direct to pump to see if its a lack of water volume coming through causing the engine to overheat,if so I will be putting a separate thruhull intake.

g a separ