Ball Bearing Autoprop Assistane

[MikeHoncho]

I picked up two H5 ball bearing Autoprops the other day. I tore each one down prior to purchase and found one prop had brinnelling (sp) on several of the blade large bearing surfaces. The hub is fine the surfaces are not terrible but i can feel it when running my fingernail around the surface. I have been in contact with Brunton and King Propulsion who is the US distributor throughout the adventure so I have some insight to what I have.

One prop will get a bearing rebuild kit which I will do and the other will need to be serviced/machined by Brunton at a expense of about $600. What I was told is that there is a possibility that they will not be able to do it making the prop worthless. Obviously I will have conversations with them prior to sending it. What I would like to is to hear from those who have experienced this service and what has made/not made the prop serviceable (how bad does it actually need to be).

 

[fstbttms]

You buy the pair that were for sale over at Cruiser's Forum?

 

[MikeHoncho]

No, local (South Seattle) on CL. Have a link?

 

[fstbttms]

No, local (South Seattle) on CL. Have a link?

For Sale: Brunton Autoprops - Cruisers & Sailing Forums

Greetings all, I have two used, not sure how much as they came aboard a cat we purchased as spares, Brunton 3-blade Autoprops. They appear to be in excellent shape, although I do not have any zincs

www.cruisersforum.com

But they were sold.

 

[MikeHoncho]

Found it, actually yes and not for that much. $1200 for both. I wasn't going to say how much I got them for but since the price is posted I guess I'll say being it was not anywhere near what he originally listed them for. Locally he had them at $1500 for one $2000 for both. The seller was a nice guy we actually are where in the same profession and have a lot in common. I spent about 3 hours looking at his cat he is rebuilding and tearing down the props at his slip. I would not hesitate entertaining his other props (confirm conditions of course) he has for sale. He's good people.

 

[Ben4195]

I had my H5 prop serviced by Bruntons a few years ago. Cost $600 like you said, but it was (and still is, knock on wood) like brand new when I received it back. Might have been brand new, now that I think of it. It was all shiny and pretty again.

 

[MikeHoncho]

Did they machine it to accept replaceable bearing races? How bad did the original races look?

 

[sailme88]

I have a three blade auto prop. Lots of likes and dislikes...Had it serviced this winter. between the kit and labor fee it was around $750.00. The only difference this spring was that it had a nice shine on it when launched.

Pros: a lot less prop walk. Cons: can only get the engine up to 2300rpms
backs down real nice delivers a vibration at low rpms
less drag when sailing. expensive to work on
not that big of a bang for the buck
limited shops that service

It came with the boat.. I would NEVER, repeat NEVER buy one myself

 

[MikeHoncho]

I have a three blade auto prop. Lots of likes and dislikes...Had it serviced this winter. between the kit and labor fee it was around $750.00. The only difference this spring was that it had a nice shine on it when launched.

Pros: a lot less prop walk. Cons: can only get the engine up to 2300rpms
backs down real nice delivers a vibration at low rpms
less drag when sailing. expensive to work on
not that big of a bang for the buck
limited shops that service

It came with the boat.. I would NEVER, repeat NEVER buy one myself

How much speed was lost from the low rpms?

 

[Hayden Watson]

I love the H5 on my C30. It has a Universal M25XP and pushes the boat well. One if the things that I realty like about it in addition to those already mentioned is that at idle speed it is almost like being in neutral. As you rev it up it gets progressively significantly more powerful. When docking, I will drop it into reverse when still about a boat length out and it barely slows the boat. Then just give a quick rev and it stops on the spot. If I am motoring and need to stop quick at cruise speed, I can quickly throttle to idle, jamb in reverse and rev WOT and stop in one boat length!
One thing to note with the AutoProp. When sailing in neutral, it will spin in the opposite rotation of motoring and create more drag than if it were a 3-blade fixed prop. Because of this reverse spin when freewheeling, I need to lock the transmission by putting it in FOREWARD not reverse. If I lock it in reverse like a normal prop, it will slip and cause damage.
This is all outlined on page 4 of my owners manual and I have found it to be completely true.

 

[sailme88]

How much speed was lost from the low rpms?

I can't answer that question with any authority as the prop was on the boat when I bought her. But, at 2300rpm the speed over the bottom is around 6.5kts in neutral conditions.. against the tide..5.8kts and if you add a stiff breeze on the nose..5.3 kts.

Now by comparison, a sistership with a tradition 3 blade prop does about the same speed at 2800 rpm and has the expected prop walk..

 

[Hayden Watson]

I only have experience with my C30 with the AutoProp installed but this is what I find.

• I prefer to run at 1900 RPM because it is much quieter and smoother and that gets me 5.4 knts.
• If I go to 2200 it get 6.0 and
• 2800 (which is rough) will come to 6.2-6.4.
• When you shift into gear at idle there is almost no perception of impulse or drive but after a bit the boat will be going 2.5 because it repitches itself as the water starts to flow over the blades.
• It has a little prop walk to port but not much and I can back to port and starboard.
• If left in neutral when sailing, it will spin very aggressively and create lots of drag but I can prevent it from turning by tying a piece of string to one of the flange bolts.
• When motor sailing with pretty much any breeze I hit hull speed of 7.1
• There are good RPM's (1400, 1900, 2200) that are smooth and the rest set up a harmonic vibration that rattles the dishes. If you get vibration, play around with small 50 rpm changes until you find the sweet spots.

 

[MikeHoncho]

I can't answer that question with any authority as the prop was on the boat when I bought her. But, at 2300rpm the speed over the bottom is around 6.5kts in neutral conditions.. against the tide..5.8kts and if you add a stiff breeze on the nose..5.3 kts.

Now by comparison, a sistership with a tradition 3 blade prop does about the same speed at 2800 rpm and has the expected prop walk..

That seams like a massive pro to me

 

[MikeHoncho]

Got the rebuild kit today.

 

[Hayden Watson]

Hopefully you will take photos of the progress and leave those of us who will be following in your footprints a clear path to follow.

 

[MikeHoncho]

Dagnabit, now I have too.

 

[Hayden Watson]

Dagnabit, now I have too.

I think you said that one of your props is the new style and the other is the old. Which one are you rebuilding?

 

[MikeHoncho]

Both are ball bearing ( old style) H5s

 

[MikeHoncho]

Did a detailed breakdown of both with wire brush cleaning. One prop will need machining the other will need it in the future I believe. The specs for torque if them is way to loose in my and others on the internet. I tightened them up to where you can just feel resistance then backed off a smug (technical term). I’m researching hookah system and when put together I’ll install it myself.

 

[Hayden Watson]

I hope you enjoy yours as much as I have enjoyed mine for the last 22 years. It has never given any problems.

One thing to note is that you must lock the shaft or it will create more drag than a non-spinning fixed 3-blade prop. If it cannot turn, the blade feather and create almost no drag and takes almost no force to keep it from spinning. On distance races when I need to run the engine to charge the batteries, I tie a single piece of builders string to one of the coupler bolts which holds the prop with the engine running in neutral.
As soon as you release the shaft, it starts to spin in the reverse direction which is why on my Hurth transmission I need to leave it in forward gear rather than reverse. once it starts to spin, the blades increase the angle of attack and start creating drag which makes it spin faster and create even more drag. It is like sailing with the engine running in gear in reverse.

I know that everything says to shift a Hurth into reverse but Bruntons (and Hurth) will tell you to do the opposite to normal with an auto prop because it freewheels in the opposite direction.