The Kiwi prop in reverse is fixed at 23 degrees...maximum pitch
. Most transmissions have a lower ratio for reverse. Means you kill the engine
, many times, when going into reverse or you overload it. Doesn't mean I'm trying to make 2400 RPM
in reverse. It means the prop pitch
is proper by the amount of rpm
you can obtain under max throttle. You should know this as that is how a prop is sized. My maximum rpm in reverse is 1200 rpm. It means I have WAY overloaded the engine
. It's a bad thing and leads to significant carbon buildup or killing the engine under docking
manuevers. Kiwi props knows about this problem and everyone has it....some worse then other...all depending on the reverse transmission
ratio. Idle engine RPM's is critical and specified in the manual for the props. Not running any engine accessories while reversing is also critical. Everything must be off while manuevering. If you have a higher reverse ratio then you'll be okay, but few boats have this. If not then you'll have problems...most people do, especially as time goes on and the blades approach the point of needing lubrication.
I have been in close contact with Kiwi props, have even been to their shop and had the props rebuilt with smaller blades. Excellent support from the owner John Blundell. Absolutely terrific support. Problem remains with the reverse however...it's a bad thing to kill the engine (repeatedly) when trying to pull into a marina and approaching the pier.
The material is a fiberglass/plastic composite. It is INCREDIBLY strong. I was given a sledge hammer to hit a blade held at the root in a vise. Impossible to break and far better then a bronze
blade, especially for manufactoring and running into things. Wrapping a line around it while underway won't hurt it or distort it. Unfortunately it promotes growth. Bronze
doesn't. The kiwi prop blade surface is very difficult to keep ANY anti-fouling
on as it's very slick. You can paint
bronze. I saw one boat
which got re-hauled 4 hours after being splashed from the boat
yard. The anti-fouling
had worn away completely at the blade edges and another 10 hours of operation would have meant no antifouling at all. It was a hard anti-fouling (micron 66). I'm now using Propspeed and will see how that holds up. It can only be applied by the boat yard and cost $150 per prop to apply. The boat yard won't warrant the application on these blades due to the material but feel that it will be the best thing and should give good performance. This is an issue of importance but in itself would not keep me from buying
these props again. I can always scrub the props and prefer this to having the bronze blades. The reverse issue is the main problem as it puts my boat into jeopardy and is ruining my engines.
Since I originally purchased my props a few improvements have been made. An o-ring at the base of the blades to keep the lubricant in, a small shaving on the blade edge, and most props now use stainless steel
shaft nuts rather then the plastic ones which had to be burned off.
Pitch ratio (forward) is set by turning a set screw on each blade. No means of measuring it is possible and you rely on turning each set screw the same amount. Not a big deal at all. No reverse pitch adjustment is possible. This is a big deal.
Summary: Great props with big reverse issues but almost all props of this type have some kind of issue. Very low cost and good performance under sail and motoring. Great customer service
. Easy and cheap
to replace blades. I don't recommend this prop for any boat with low reverse ratio (many boats).