I swapped the standard yanmar 2 blade alu prop (kept as spare now) for a maxprop 3 blade feathering prop. The appropriate model all depends on your sail drive, i have a SD50 on a 4JH4E,

MaxProp 18" was advised, can't remember the pitch OTMH, but can get back to you.

 

I was advised (by Hanse France) to go for feathering and not folding prop, i must say performance is fantastic and drag minimal.

 

To order a prop, you'll need to provide motor, sail drive references, as well as confirmation of shaft rotation from stern. The manufacturers will provide the adequate prop blade size and pitch.

 

i have many quotes for feathering props should you need them ?

 

cheers

stephen

The web site is http://www.maxprop.it - www.maxprop.it

I think you have 10% more speed when sailing, but 5% less speed when motoring against a fix propeller.

The propeller works also very well in reverse, better than a fix propeller.

I have Yanmar 4JH4E with saildrive SD 50.

 

 

When I go above 2500 revs the steering wheel is shaking quit a lot.

 

I have never had a folding or feathering prop before so I don;t have any experience with them. Of course I checked with the dealer but they said that I have the correct one.

 

Does anyone else have this experience.

Dive behind the boat and find out.

greetings Marcel and succes.

 

I don't have big experience with propellers but the noise you have could be caused by cavitation (the prop blades are pushing the water harder than normal and it boils at the back side where the pressure is lower than it should. This can be caused by very high pitch selection- the prop is trying to move the boat faster than she wants.Later the bubbles collapse and this noise and light is produced. Finally at 2500 RPM the bubbles reache the rudder and cause the vibrations. If I am true the boat will move faster than before for the same engine revs.

If this is the case both the engine and the propeller will have problems (faster wear).

Propeller selection is an art and not science since the power curve of the engine has to be matched to the friction curve relative to speed of the hull. The engine power is known but the hull resistance depends on the hull shape, the hull surface (clean,dirty or very dirty) and the sea conditions.

So the correct diameter and pitch can only come from other (failed) trials.

I think the maxprop has variable pitch, so you can dicrease it when the boat is out of the water.

Following I found in Wikipedia :

Just as cavitation bubbles form on a fast spinning boat propeller, they may also form on the tails and fins of aquatic animals. The effects of cavitation are especially important near the surface of the ocean where the ambient water pressure is relatively low and cavitation is more likely to occur.

For powerful swimming animals like http://en.wikipedia.org/wiki/Dolphins - dolphins and http://en.wikipedia.org/wiki/Tuna - tuna , cavitation may be detrimental because it limits their maximum swimming speed. ^{http://en.wikipedia.org/wiki/Cavitation#cite_note-3 - [4]} Even if they have the power to swim faster, dolphins may have to restrict their speed because collapsing cavitation bubbles on their tail are too painful. Cavitation also slows tuna, but for a different reason. Unlike dolphins, these fish do not feel the painful bubbles because they have bony fins without nerve endings. Nevertheless they cannot swim faster because the cavitation bubbles create an air film around their fins that limits their speed. Lesions have been found on tuna that are consistent with cavitation damage.

Interesting!

 

Panos is right about cavitation.  May be it helps if you reduce the pitch, but from experience I can say that Max prop is always making more noise and vibrations than other propellors.

 

A fixed propellor has an optimal blade shape.  When running the outer diameter of the prop (=end of the blades) have a faster speed in the water than the innerside of the blade, near the shaft.

A fixed (and most folding) propellerblade is designed for this different speed.  You have a kind of torsion of the blade: the further you go to the outer diameter, the smaller the angle in the water.

 

A maxprop has completely flat blades.  If feathering, a flat blade has the lowest drag (resistance) and there is the maxprop designed for.

But when the propellor is running by the engine, the blades get an angle in the water. 

This angle (pitch) is the same all over the blade, from shaft to the outer diameter and this is not optimal.

At the shaft the pitch is too less and at the end the pitch is too much,  creating cavitation.

For a maxprop this is normal, but it creates more noise and vibrations and the efficiency of the propellor is lower, resulting in a bit smaller speed (maybe 0,1 or 0,2 kn).

A three bladed maxprop must have less vibrations than a two bladed maxprop.  (I don't know what you have installed)

 

Check the pitch of the maxprop.  If your engine has problems to reach the max revolutions and starts smoking, the pitch is too high.  Also if the response of the engine is slow, it is an indication of a high pitch.

If the engine is running at high revolutions, but your boatspeed is still low, than the pitch is too less.

 

It is just trial and error, but complicated by the fact that your boat has to be lifted for adjustment of the propellor.

 

Hope this information can help you.

 

Regards,

Wessel 

 

 

 

 

Any suggestions from any other expirianced member ?

/Steen

/Steen

Hi Alex in a nut shell i have had 2 kiwiprops on a 370 never ever again  David

 

why not you ask. Because you can not rely on them reversing pitch when you need it, like trying to stop in the lock before you pile into the boat infront. kiwi said it needed grease, well it had been in the water only six months. the second one did the same. david

/Steen

http://www.yanmarmarine.com/uploads/products/pdf/JH/3JH4E_TechData.pdf - http://www.yanmarmarine.com/uploads/products/pdf/JH/3JH4E_TechData.pdf

 

but i'm surprised you have the 40hp 4JH3,

because on all 411's it was first the volvo 55hp,

and finally the yanmar 4JH4 the last 2 or 3 years. didn't know a 40HP was an option.

 

as for sail drives, i have SD50 ,

 

http://www.yanmarmarine.com/uploads/products/pdf_saildrive.html - http://www.yanmarmarine.com/uploads/products/pdf_saildrive.html

 

The Yanmar 4JH3 with a SD-40 installed on the 411 2004 is rated 56 HP @ 3800 RPM.  Not 40 HP which is the 4JH4.

Thanks

Alex Danciger