Still have the original two blade prop on the Boat and was wondering if anyone has success stories on potential upgrade options. Limited Prop Shaft length for upgrade is about 5" from Strut to threads for prop nuts
Hunter 40.5 - Prop Upgrade
- Thread starter Censina
- Start date
What do you want to accomplish with a new prop? Better sailing? Better reverse? More forward thrust?
Not disappointed in what our performance is......just being told by fellow boaters there are more efficient options. Primary purpose would be more forward thrust with better efficiency ( Less Drag, lower RPM requirement under motor). We don't race and reverse are not an issue at all.
If I were in your position, I'd go for a MaxProp 3 blade (if you only use the boat occasionally) or 4 blade (if you use the boat a lot). It is an incredible step up from a fixed prop. We love our MaxProp.
However, if you make the change from a 2 blade to any other, you must get the correct prop. You will need to know the hull shape, engine hp, trans reduction gear, shaft taper, key way size and shaft diameter. With this info you can go on any prop manufacturer's web site and find the right prop.
However, if you make the change from a 2 blade to any other, you must get the correct prop. You will need to know the hull shape, engine hp, trans reduction gear, shaft taper, key way size and shaft diameter. With this info you can go on any prop manufacturer's web site and find the right prop.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,945
Ok What do you have right now. Do you have a picture of the prop?
I wanted a similar results. I went from this original old design...
to this...
Big design change. If original had been a more modern prop, there would not have been as much change.
I wanted a similar results. I went from this original old design...
to this...
Big design change. If original had been a more modern prop, there would not have been as much change.
I won't pretend to know all the answers and each boat is different. In general a 2 bladed prop will be the least expensive option with OK performance sailing and motoring. A three bladed prop with generally get you more forward and reverse thrust at the expense of sailing performance. From there you enter the world of folding and feathering props and second mortgages to pay for them. At the low end are Martec folding props, simple, effective, relatively inexpensive. At the other end of the spectrum are Flex-o-Fold and Max Props which are feathering props.
The prop size and pitch will be determined by the engine and its "sweet spot" and prop clearance. The tips of the prop need to have sufficient clearance from the hull in order to be effective. The least critical dimension is the prop shaft length, if you need a few more inches in length, a longer shaft can be installed. The shaft will be the least expensive part.
I've had a 2 Blade Martec prop on my Sabre 30, it worked well while sailing and motoring forward. Plenty of thrust. Reverse was a little weaker, but manageable.
Currently I have 3 Blade Max Prop on my Sabre 362. It is a feathering prop and has good thrust in forward and reverse. Max Props use flat blades which gives them about equal thrust in forward and reverse and increases prop walk. Again, once you get used to the prop walk and learn to use it is not a big deal, just the first time you throw it in reverse and the stern jumps 3 feet to port. Catches your attention.
Ask around do some research on what you want and then contact the prop manufacturers and they will guide you throw the size and performance issues.
The prop size and pitch will be determined by the engine and its "sweet spot" and prop clearance. The tips of the prop need to have sufficient clearance from the hull in order to be effective. The least critical dimension is the prop shaft length, if you need a few more inches in length, a longer shaft can be installed. The shaft will be the least expensive part.
I've had a 2 Blade Martec prop on my Sabre 30, it worked well while sailing and motoring forward. Plenty of thrust. Reverse was a little weaker, but manageable.
Currently I have 3 Blade Max Prop on my Sabre 362. It is a feathering prop and has good thrust in forward and reverse. Max Props use flat blades which gives them about equal thrust in forward and reverse and increases prop walk. Again, once you get used to the prop walk and learn to use it is not a big deal, just the first time you throw it in reverse and the stern jumps 3 feet to port. Catches your attention.
Ask around do some research on what you want and then contact the prop manufacturers and they will guide you throw the size and performance issues.
Ditto jssailem.............installed 3 bladed fixed prop (Michigan) on all my sailboats to maximize hull speed and maneuverability while motoring. Coated it with 2 coats of barnacle spray paint per boatyard recommendation.
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See attached----- thanks for all the recommendations will look into them. Going to clean this up in the next week but is what fostered the question
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![20200411_153906[6649].jpg](/data/attachments/155/155805-7bd0c496e9f0a973d1854ef33ddbc698.jpg)
Many years ago I changed out the 2-blade for an AutoStream 3-blade feathering prop. At the time it was the only feathering prop that could be adjusted for pitch both forward and reverse in the water. Also able to be greased in the water too. Since I was concerned about getting the pitch exactly right I thought that was an advantage. But now I think other feathering props can be pitched in the water. and at the time the cost was about $500 less than the Max Prop.
Turned out that no pitch adjustment was required. It was perfect from the factory.
The other factor for me was that the AutoStream was stainless steel, so there is no metal dissimilarity between the shaft and the prop.
The performance change was impressive. Reverse thrust is like having power brakes. Forward thrust is greater and I am able to punch thru current and waves easier.
BTW, I don't race. I just figured that if I was going to upgrade, I may as well go for the best possible change with the least disadvantages. The only disadvantage of this prop was the cost.
What ever you do, if you decide on a folding or feathering prop, I would recommend installing a line cutter to protect the prop from entanglement damage.
Turned out that no pitch adjustment was required. It was perfect from the factory.
The other factor for me was that the AutoStream was stainless steel, so there is no metal dissimilarity between the shaft and the prop.
The performance change was impressive. Reverse thrust is like having power brakes. Forward thrust is greater and I am able to punch thru current and waves easier.
BTW, I don't race. I just figured that if I was going to upgrade, I may as well go for the best possible change with the least disadvantages. The only disadvantage of this prop was the cost.
What ever you do, if you decide on a folding or feathering prop, I would recommend installing a line cutter to protect the prop from entanglement damage.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,945
Ok. You have a decent design to a prop serving as “auxiliary” power for a sail boat. I think an investment in cleaning up the prop, perhaps even sending to a prop shop for a tune up would be worth it.
Two blades make less drag for a sail boat, especially when aligned behind the keel.
Two blades make less drag for a sail boat, especially when aligned behind the keel.
I have had a two blade Slipstream SS geared folding prop on our boat for 15 years. It made a significant improvement in light air and pointing. I would personally never go back to a fixed prop. However, it does look nice on the fireplace at home...
Being ignorant of diesel stuff on a sailboat..... how does the prop align? Does that happen by natural drag or do you have to set it somehow?
for a Flex-o-fold. Although it sounds like the OP is more interested in motoring performance than sailing. I love the FOF sailing performance, but motoring is the same or maybe just slightly better than our fixed 3 blade was.