Propellor specs

[RenoirIII]

Hi All,
I have a Bonbridge 27 and one of the two blades came off the propellor (not sure how???).
I'm now looking at replacing it but would like to source a prop before I take it out of the water to reduce the hard-stand cost.
I measured the shaft behind the gearbox of my Yanmar 1GM10 which is 1 inch. The gearbox has a 2:1 ratio. Horse Power (hp) 8...

Other info that may be important???
Hull Construction Material : GRP
Hull Type : Mono
Deck Construction Material : GRP
Length (feet) : 27'3" feet
Length (m) : 8.3 m
Length Waterline (m) : 6.6 m
Beam/Width (feet) : 9 feet
Beam/Width (m) : 2.75 m
Draft (feet) : 5'6" feet
Keel/Ballast : Fin keel, cast iron 1090kg
Dry Weight (kgs) : 2420 kgs

Any ideas on potential prop specs?

Thanks in advance for your thoughts...

Renoir

[a64pilot]

You know, honestly call the prop shop where you will buy the new one with all your specifics, Boat waterline length, weight etc and ask them.
You have a better shot at both getting it right that way, and if it’s way off, you can be nice and remind them they speced the prop and they may exchange it or something.

[sonofasonofasailer456]

There are all kinds of prop calculators on the www, fill in your all info it will give recommendation

[Island Time O25]

http://www.marinedieseldirect.com/ya...ences/prop.php

I'd check on craigslist, ebay, etc, first. No need to spend big $$$ if you can find it used there. Unless you need it ASAP.

[RenoirIII]

That was very helpful Island Time...
I need a 14 x 8.
However, I can buy this 15 x 10 second hand.
Obviously the each propeller is 1/2' longer and the pitch is more acute.
The boat is a bit more beamy then average so this may play a role as well???
Would it make a lot of difference or just marginal in your opinion?

[GrowleyMonster]

Originally Posted by RenoirIII

That was very helpful Island Time...
I need a 14 x 8.
However, I can buy this 15 x 10 second hand.
Obviously the each propeller is 1/2' longer and the pitch is more acute.
The boat is a bit more beamy then average so this may play a role as well???
Would it make a lot of difference or just marginal in your opinion?

That may work. The big question is whether there is enough clearance with the hull. If the prop already turns 1-1/2" or less from the hull, you don't want the bigger prop. A prop shop can cut it down for probably about $75, maybe less, being two blade. Is this a folding prop? The 2" of pitch is not a real big deal.



If you wait, the exact prop you are looking for will show up on fleabay. You might also enquire at the yacht salvage shops, and there is one in Carabelle, FL but I don't remember the name of it, and one in Kemah TX, The Boaters' Resale Shop of Texas (713) 614-8884.

[boatpoker]

A blade fell off !

Before I did anything else I'd find out why.

My first thought would be stray current corrosion and if that is the case, your new prop will also suffer quite quickly. If you are in North America have an ABYC Certified Corrosion Analyst look at it. If they use the word "electrolysis" , they don't know what they are talking about, hire someone else.

Any photos ?

[GrowleyMonster]

Originally Posted by boatpoker

A blade fell off !

Before I did anything else I'd find out why.

My first thought would be stray current corrosion and if that is the case, your new prop will also suffer quite quickly. If you are in North America have an ABYC Certified Corrosion Analyst look at it. If they use the word "electrolysis" , they don't know what they are talking about, hire someone else.

Any photos ?

And that's a good point. How do your shaft zincs look? If they disintegrate when you tap them with a hammer, you don't have zincs at all, for all practical purposes. Be sure you put one or better yet two on the shaft when you reprop. You can also do it in the water but be careful not to drop the screws. They protect not only the prop but also shaft and any other metal connected to them. They are cheap enough to carry a couple of spares. If you have pencil zincs in your engine cooling system, it is probably a good time to change them, too. Along with pump impellers, these are a good thing to routinely change annually, being both cheap and critical. Belts, too.