Propellers

[Setsail_2015]

Time for new props for my 08' Lagoon 420. She has 2 - 38hp, 3-cyl Yanmar Diesel engines . Any suggestions on what kind I should buy? The old one's weren't original.

[UNCIVILIZED]

I'm a big fan of MaxProps, or others which feather, & have as much thrust in reverse as in forward. And with MaxProps you can adjust the pitch on most of them with the prop on the shaft, in the water. Which helps when tuning a prop to your specific boat, & engine. Meaning beyond the standard fomula generated pitch recommendation for your boat & engine(s).

[westwinds]

The problem is the current propellers might not have pitch and diameter optimized for your engines so you should not trust the current diameter and pitch to be correct. If the engines are not original, them another confusing factor. The standard formulas for propeller diameter and pitch only work for a mono hull, maybe there are formulas that work for a catamaran that I am not aware of, but the hulls are so narrow and long that the wake that is formed does not take nearly as much energy at higher speeds as a mono hull. Check with manufacturer about pitch and diameter. I also agree with Uncivilized's comments. The drag caused by the propellers goes up a lot faster than the speed of the sailboat so feathering should make a big difference on speed. If the propellers have variable pitch, then adjustments can be made until the correct match is made for pitch. Keep the same diameter or larger. Larger means better efficiency and less possible problems with cavitation. Make sure you have 10% or more of the diameter of the propeller for the distance from propeller to bottom of hull.

[GordMay]

Greetings and welcome aboard the CF, Setsail.

[fstbttms]

Originally Posted by UNCIVILIZED

...with MaxProps you can adjust the pitch on most ALL of them with the prop on the shaft, in the water.

There, fixed that for you.

[MrSteve007]

Count me as another vote for a Max-prop. I put one on my '02 Hunter 326 with a Yanmar 2GM20F engine and have been extremely pleased. Pricy, but the upgrade in performance is well worth it.

[valhalla360]

1) Why are you replacing them? Unless damaged, they pretty much last forever.
2) What are your priorities? If you race or are an intense sailor, the extra for folding/feathering props makes sense. If you are a cruiser who just happen to sail, you can save a lot by using fixed blade props and there is no worries about mechanical issues if they get all crudded up with growth.
3) Did the old props work well? If they got you up to normal cruising speed and the engines could still get up to full RPM, don't try to fix what ain't broken

[MrSteve007]

Originally Posted by valhalla360

1) Why are you replacing them? Unless damaged, they pretty much last forever.
2) What are your priorities? If you race or are an intense sailor, the extra for folding/feathering props makes sense. If you are a cruiser who just happen to sail, you can save a lot by using fixed blade props and there is no worries about mechanical issues if they get all crudded up with growth.
3) Did the old props work well? If they got you up to normal cruising speed and the engines could still get up to full RPM, don't try to fix what ain't broken

For me, the stock 2-blade prop just didn't have enough "bite" when the going got rough. When handicapped with a 31' length and an 18-hp motor, I found the stock two blade prop really begins to let down when pounding into heavy seas. In 4-6' seas and a strong headwind, I'd see speed-over-ground as slow as 2 knots when climbing into the next wave. I was close to tearing out the perfectly good 2GM Yanmar and shoehorning a more powerful 3YM to get a bit better performance when out in rough conditions.

And in the Puget Sound, due to geography, you're either pounding into the wind and waves, running downwind - or motoring on flat calm. Beam reaches are rare.

With a 3-blade, I've noticed considerable performance improvements, both under sail in light winds and especially when motoring into weather. And for me, it was far cheaper than an engine swap.

[sailah]

I love my max prop. And I've had an excellent customer service experience with them, had a question about adjusting pitch and they walked through pics I sent them and called me back quickly to discuss. And this was for a 12 y/o prop.

[Nineteen]

I love my Hydralign feathering prop on my C380. Really well made and very simple to maintain compared to the older style Max Prop on a friends Valiant.
Mine is coming up to 17 yrs old now👍
Cheers
Tom

[thaisail]

Originally Posted by Nineteen

I love my Hydralign feathering prop on my C380. Really well made and very simple to maintain compared to the older style Max Prop on a friends Valiant.
Mine is coming up to 17 yrs old now[emoji106]
Cheers
Tom

Tom, what model and size Hydralign prop do you have? We are looking at buying a Hydralign 20" Aperature B 3 blade and we heard that they cannot be greased underwater! If this true, the propeller will have to be pulled off underwater which could be a challange.

[Nineteen]

Originally Posted by thaisail

Tom, what model and size Hydralign prop do you have? We are looking at buying a Hydralign 20" Aperature B 3 blade and we heard that they cannot be greased underwater! If this true, the propeller will have to be pulled off underwater which could be a challange.

Hi Thaisail

We have the 3 blade 'Senior' 16". You can re-pitch in the water if you like and grease it in the water without any issue.

If you pull the anode the grease nipple screws straight in. It also screws into the plug in the hub.

I just pump in until I get fresh grease to come out.

I am using a Fuchs Renolit NLGI 2.

Cheers
Tom

[Down East]

I went from a fixed 3 blade to a Flex-Fold 2 blade folding for my old boat with a Yanni 3gm30 after great feedback from another cruiser friend and reading reviews.
The light air performance difference was massive!
I was concerned about wind/chop going to a 2 blade, but the blades have a lot of surface area that give excellent bite on the water and less prop-walk in rev than the old 3 blade.
My new boat came with a 3 blade Flex-Fold and it’s even better.