KIWI feathering propellors

[wizard]

Whilst looking for folding propellors on the internet for my sailing yacht I came across a feathering prop (3 flat blades) called a Kiwi. Just wondered if anyone has any practical experience or knowledge of this type and does it improve sailing speed.

 

[MrFish]

The Kiwi feathering prop was developed in New Zealand, and seems to be quite successfull, although I do not now how well they last. I've no reason to think they wont last, either!. They are very easy to fit, can be adjusted with the boat in the water, and are easy to maintain - basicaly nothing to do.
They are otherwise another feathering prop - reduce drag while sailing, giving an extra 3/4 to 1.5 knots.
The pitch can be adjusted to suit your boat, they give full pitch immediately in reverse, and the blades align with the water flow when the shaft is not powered. The blades are not flat, but shaped, and made from some sort of resin ? compound.
The designers web site used to be www.kiwiprops.co.nz I think they are made in UK now, as well as NZ.
I hope this helps - they are way cheaper than the others in NZ, but I've no idea how they compete in UK.

 

[boatmike]

Having been alerted to these after visiting LBS, I returned to look at them. I am not a hydrodynamicist but frankly I think the flat blade looks very inefficient and they are quite open about the fact that the composite blades are a lot less robust than bronze ones. It looked to me that their impact resistance was suspect and although they obviously reduce drag when sailing they would not be as efficient as a Darglow feathering prop or better still a Bruntons Autoprop. Both are more expensive of course.......

 

[AlexL]

I've just ordered one and I thought they looked pretty good. A proper curved blade is not really compatible with a folding or feathering function so it will allways be a compromise. Modern composites are generally excellent (most turboprop aircraft propellors are composites), and I'm not sure they are any less robust than bronze blades. However under impact I would rather the blade broke off rather than transfering the full energy from the impact into the transmission (A prop blade is considerably cheaper than a saildrive unit!), and the blades will be really, really cheap as all the cost in composities is in the tooling, once the blade is tooled up the cost of banging out another blade is negligable. Bottom line however is that, yes a Brunton Autoprop may well be better, but at twice the cost, I'm damn sure it ain't twice as good, and I can buy a kiwi prop and most of a cruising chute for the price of a Bruntons Autoprop! I know which of those two combinations will make my boat go quicker!

 

[macd]

I was seriously thinking of buying one, but it turns out they won't even come close to fitting my boat, a Rival 32, because of the way the blades feather back aft. I suspect many older boats will have a similar problem.

The UK importer for Kiwiprop can be contacted at sales@vectamarine.com

 

[paulmcquillan]

We've had one for several years on our boat and love it. Added about 1.2 knots to our sailing speed.... Caveat on our boat: the prop shaft is offset to port and not hidden behind the keel so the performance improvement was wonderful.

Don't think impact damage would be an issue unless you hit a log or container. Good news is that a replacement blade is about $50 and they could ship it quickly. Mfg says that the Zytel (DuPont) blade would break before the bonze arms, and that would be an advantage. You could replace with a snorkel and allen wrench while still in the water. Mfg also said they've only had two blades break worldwide... both when someone backed into an immovable object.

Overall our sailing speed is up, our speed under power is up (from 5 1/2 to 7), vibration is down. Back then the mfg even shipped our prop express, at his expense, so we could use it for the last race of the season.