Autoprop ?

[jose r vigil]

Dear alan

Very shortly

1.- I was shocked to read that you think BRUNTONS have gone beyond their call of duty. English is not my mother tongue. May be I'm missing something?

2.- What I expect to see in an Analyzer screen is

(Engine rpm/gear ratio)x 3
Fq Hz=__________________
60

And the subsequent harmonics.

3 is number of blades
60 is seconds in minutes

3.- It is true that Amel is still recommending AUTOPROP. I'm again very sorry. I have tried to edit my post as the person who gave up becuse the bearing problem was the Amel owner and NOT chantiers Amel. I wasnt able to edit my post. Alan could you please tell how to edit that part of the post?

I'm stealing hours of sleeping to write theese posts and my mind was blurred for writing too late. I have made a mistake in the interpretation of the German engineer e mail. His English is sometimes a bit German.

4.- The Amel supermaramu falls into the cases of GOOD WORKING for the AUTOPROP I have disclosed following my theory as per my post #106. I'm repeating here part of my post for your convenience

+++++++++++++++++++++++++++++++++++++++++++
the AUTOPROP can only work in

a) Optimized faired skegs with overhanged cutlass bearing housings

b) Long shafts with thin single shaft strut ( as far as possible to the hull and the skeg)

c) The clearances to hull and skeg should be maximized anyway to the extreme.

d) In well designed saildrives when the boat is less than a 47 footer so the engine is less than 75 HP and the saildrive neck is as long and as thin as possible, but also has a strong bearing on the shaft tip. This last issue is a bit misleading in mmarketing terms as the price and design of the AUTOPROP call for larger yachts and not for small sailboats.
++++++++++++++++++++++++++++++++++++++++++++

The Amel Supermaramu is a special desing and falls in both the a) and the d) cases. The saildrive is part of the keel and it is very well faired. An excellent idea.

After my experience I dont recommend to choose an AUTOPROP in any modern straight skeg hull.

5.- The US rep is literally "missing in action" His e mail box is bouncing all my e mails since his last and only e mail in months two weeks ago.


6.- Alan you seem to be well informed from BRUNTONS, yesterday they refused a cash back and directed me to their US rep again. Good customer service.

My nightmare is lasting EIGHT MONTHS NOW.

Best regards to all sailors

Jose

Originally Posted by Alan Wheeler

I think Bruntons have gone beyond the call of duty in regards to offering you anything. It was not them that you bought the prop from. It is the US dealer that you dealt with and it is them that should be taken to task on this. I think they have so far shown that they are not offering the best of service on behalf of a fine product and manufacturer. The US distributor should be either sorting your problem or refunding your money.
In regards to FFT, I am not saying they won't tell you anything, what I am saying is, what use is the information that it will tell you. You already know there is a noise and a vibration. Seeing that on a screen is not going to help you. Either the skeg can be modified to solve the issue, the prop can be changed to suit the boat better, or if niether are possible, then there is nothing that can be done and the US supplier needs to refund you.
I confirmed that Amel are still using the Autoprop and report that they are very happy with them. They know of no issues with any of their vessels.
If the problem exists with just some boats, then it is very much only a few designs and I guess each would have to be solved on a case by case basis. As in, maybe the skeg or the prop could be altered to suit.

I also didn't understand that Dave Kall's issue with the shaft bending had actually been resolved. That is good to hear. So it is mostly a speed thing now. A smaller prop may solve that, but speed at low RPM may not be an issue as such, but just the way it works.

[jose r vigil]

Dear Alan

Just think how do you will feel if you were in my position having such a beauty on the yard instead of enjoying the sea.

Pic taken by Susan in palma Audax marina RCN palma Spain in one of the many haul outs, wearing the AUTOPROP

Jose

[Alan Wheeler]

OK, I will try to be clear. By the way, your english is very good.
Firstly I understand your heart acke and anguish. Beautiful vessel by the way. What I am trying to say, is that the US distributor, the company that sold you this prop, should be also solving your problem. If they have solved you something "that is unsuitable for the purpose in which it is intended"( I believe is the same US consumer law as it is here in NZ, correct me if I am wrong) then they should either be trying to solve your issue, or refunding your money, or you should be taking them to court.
The only time reason (and I do believe the time has indeed come and you have a good reason) to contact Bruntons is to complain about their US distributor. They should be placing pressure on them to correctly and fairly represent thier product. IF Buntons so whish to choose to offer you another product, then that is up to them. But in reality, the US rep should be held accountable and if there is an issue with the prop, then the US rep should be dealing with Bruntons on a way forward, you should not have to. It is at a cost of time and money to have to contact them. That shouldn't be your problem.
What I do suggest is that you once again contact Adrian of Bruntons and complain in regards to the poor service that you are recieving from their US distributor and ask if they could perhaps help resolve the issue.
What I also suggest you do, is that you contact a lawyer or whomever the correct channel is in America and start legal proceedings topward the US distributor.
(could someone jump in with the correct course of action for the US consumer)
Jose, does that help? I am trying to help you here, but I am also trying to be fair for Both parties. Not leaning to one or the other side, just fair. Also please remember, I am in the middle. I don't know all the story, only what you have shared here and what Adrian has been able to tell me of the situation. I do think he is trying to be of help.

[dkall]

In general, I'll give Adrian credit. He was able to get the ball rolling on my issue. There were some email issues there too, but once I reached David and began working with him what have I hope a resolution.

As to my particular issue, I've now switched the prop and have the other to send back. I sealed the bearing from the outside with underwater epoxy and that has stopped the drip. (I don't know how long it will last but do know that when I haul this winter/spring I'll rebed the entire bearing and since it is out replace the bearing too. As I'm in the middle of a new radio installation I haven't yet run the prop to see what difference their is, I hope to this week. I have let Adrian know. He was kind enough to ask in an email where I was at. So I give him and Bruntons credit for taking the time to follow up.

As a follow up on Jose' comments with my situation. I had 30 year old engine mounts and although I never thought they were bad the Autoprop highlighted the issue. Bruntons suggested that I replace them and as my research indicated that yes the do age and I've even one source that said every 5 years , I replaced them. Then I realigned the shaft and the whipping stopped. There was still much noise and I was traveling at hull speed at 50% of my engine power. Not believe that was good for the engine and not liking how close the hull the tips were (from my reading too they were excessively close) I emailed and called Bruntons. The shipped a replacement to me, I switched props, boxed up the other and it is ready for return and hopefully as I mentioned above will be able to fully check it out this week.

[Alan Wheeler]

Thanks Dave. So with the new porp, how do clearances look now??

[dkall]

Everything looks much better. I'll be interested in comparing the "seismic" analysis to see if the noice / movment is less. Actually don't know if I'll see any change in the graph cause my guess is the engine is a big part of it thumping away and I don't think I want to take the time to figure out a way to subtract it out. Hopefully this week I'll be able to begin testing.

[jose r vigil]

Dear Alan

thanks for your reply I understand your position.

I HAVE SOME GOOD NEWS

BRUNTONS in the UK isssued a return athorization, So I'm flying to Palma today to pack ther prop back to the UK.

Yesterday I have purchased a 20 by 16 GORI prop with overdrive mode.

I will keep you infornmed of my progress and comparison between the two props which may interest some of our fellow cruisers.

Good winds

Jose

[ernest]

Dear Jose,
I have read about your hull vibration problems and I do not believe that Autoprop is the only offender. You will always have a pressure pulse in the hull when a propeller blade passes an obstacle. In you case (as in mine) you have a flat underbody and I can fully understand that your bottom "buckles every time the propeller blade passes. That will happen with any propeller and the blade shape and the distance between the blade tip and the bottom of the hull will determine how serious your problem will be.
What I am saying is that you might have the same problem with your Gori and one partial remedy would be to put an inch or so with some heavy gunk inside your boat in the area where the prop passes. Quit a common treat as far as I know.
My own experience with a fixed twobladed prop made me literally sick!
At certain rews I started to have a cold sweat and a nausea. Changing the motor rews slightly fixed the health problem but with my hand I could feel the bottom vibrating.
Bringing down an oscilloscope and an accelerometer and measuring the vibration frequency directly showed pulses two times per revolution of the prop shaft.
When I changed to a threebladed Volvo-Penta folding prop the problem dissapeared completely. I dont know if you are familiar with that product but it has scimitar shaped blades which are optimized for silent vibtationless operation. If you look at modern submarine propellers for extremely silent operation you will see something similar.

Your theory about the blade slightly changing its pitch is however still interesting and thought evoking.
Half a year ago I was determined to change to an Autoprop. I am going to chnage to a stronger engine so I have to change my prop anyway.
Now I am not that sure anymore and I really appreciate all the trouble you are taking in sharing your experiences with this forum.

The patent application would be interesting reading even if you probably will not find any answers there about vibrations.
I am however still interested in background theory about the propeller.
Have you pursued this matter?
Best regards ...

[jose r vigil]

Dear Ernest

Thanks for your feedback. You post an interesting issue. I will reply to this after disclosing my experience with Gori today.

We just hauled out yesterday to put the GORI.

First Observation No vibration at all

Second The speed in normal forward is lower than autoprop

Third The speed in overdrive mode is more or less the numbers of the Autoprop but NO VIBRATION

Fourth In reverse the stopping power is good an the yacht is pretty easy to steer stern to ( mediterranean mooring style). Not as good as the AUTOPROP.

The speed at 3000 rpm which is the crusing speed of the 3800 rpm Yanmar HTE was 7,6 knots in Normal mode and 8,6 Knots in Overdrive. we didnt rev up more as we were inside the port of palma and the traffic was heavy.

No pulling of the wheel to port in forward.

This is our first obvervation and I promise to write a more in deep feedback in a couple of months and after checking how can I use the overdrive mode.

I consider the normal mode speed a bit deceptive.

I was e mailing with GORI plant directly as I considered the size of the prop recommendeed by the importer in spain (20 by 16) was under size following my calculations as per the propeller handbook recommendations (22 by 15) .

They insisted on that size, If you want more speeed use the overdrive mode they told me.

I still think the prop is bit undersized and they dont like to recommend a bigger size because the potential problem of a overloading the engine in overdrive mode.

The real fact is in a 3800 rmp engine you dont rev up over 3200. I'm talking about real life. Some recommendations of crusing revs up to 90-95% of the max revs seems unrealistic to the best of my crusing experience.

So in my calculations I tried to match the engine to the prop maximizing the power absorved by the prop at that rpm (3200). That calls for a 22 by 15 prop.

But Sune from Gori didnt like the idea. So I ordered a 20 by 16.

Concerning your post

we didnt have a bump problem on the hull, We literally were shaked on deck by the vibration. So we can feel or heard bumps....with the AUTOPROP we feeleed like the yacht is gonna be broken in pieces. So we have a much bigger problem that simple hull bumps

Of course I know what you are talking about and my next weekend project will be insulationg the engine. The insulation in my Hanse is a bad joke.

First the foam didnt cover the stair door in the companionway. The engine room is full of absurd holes and doors all because Hanse wanted to install a 14 KW generator over the engine which makes engine service impossible.

I already removed the generator bracket ( 50 kilos of square galvanized tube) and now I can even acces the water pump (unreachable before taking the gen bracket out).

We feeled the noise was a bit down also just by taking the gen bracket apart ( resonance problem?). the bracket was screwed to the engin e bed just one inch clearance to the engine mounts.

So next I will install a new engine room insulation closing some doors and holes.

I have received some samples from a firm called acoustica. They are in Australia and not representeed in Europe up to date. The advertised insulations graphs are outstanding. i have never seen 25 dbs on 150 Hz.

you can check this at www.acoustica.com.au

The samples I have jus received are excellent. Anybody have ever used theese materials? Any feedbacks?

And after that I expect to hear my "bumps in the hull" . Now the noise is too heavy to hear although I feel they are there.

The Hanse hull is epoxy not Polyester the noises are transmitted diferently. while sailing you can not hear the water flowing in the hull , the yacht is in complete silence inside. That makes engine noise more stressing when started on.

Ernest,,,,I would like to know if you have used any products with success to treat the hull bang problem. The stern beds are over the propeller hull area and I have plenty of space to treat the hull surface inside.

I checked the Gori prop clearances to hull and skeg we have 35 % blade to the skeg and 25 % tip to the hull. I think they acceptable.

I was thinking into a redesign of the shaft as the rudder blade is far away so we have space to place a brand new strut bearing and a longer shaft which will make clearances much bigger and will put the prop closer to the rudder and far away for the skeg deadwood.

in that way I can make a glass work fairing the deadwood as per the prop hadbook recommendations.

BUT NOT THIS YEAR

Good winds

jose

Originally Posted by ernest

Dear Jose,
I have read about your hull vibration problems and I do not believe that Autoprop is the only offender. You will always have a pressure pulse in the hull when a propeller blade passes an obstacle. In you case (as in mine) you have a flat underbody and I can fully understand that your bottom "buckles every time the propeller blade passes. That will happen with any propeller and the blade shape and the distance between the blade tip and the bottom of the hull will determine how serious your problem will be.
What I am saying is that you might have the same problem with your Gori and one partial remedy would be to put an inch or so with some heavy gunk inside your boat in the area where the prop passes. Quit a common treat as far as I know.
My own experience with a fixed twobladed prop made me literally sick!
At certain rews I started to have a cold sweat and a nausea. Changing the motor rews slightly fixed the health problem but with my hand I could feel the bottom vibrating.
Bringing down an oscilloscope and an accelerometer and measuring the vibration frequency directly showed pulses two times per revolution of the prop shaft.
When I changed to a threebladed Volvo-Penta folding prop the problem dissapeared completely. I dont know if you are familiar with that product but it has scimitar shaped blades which are optimized for silent vibtationless operation. If you look at modern submarine propellers for extremely silent operation you will see something similar.

Your theory about the blade slightly changing its pitch is however still interesting and thought evoking.
Half a year ago I was determined to change to an Autoprop. I am going to chnage to a stronger engine so I have to change my prop anyway.
Now I am not that sure anymore and I really appreciate all the trouble you are taking in sharing your experiences with this forum.

The patent application would be interesting reading even if you probably will not find any answers there about vibrations.
I am however still interested in background theory about the propeller.
Have you pursued this matter?
Best regards ...

[hellosailor]

Jose, if you are going to the trouble of considering a longer shaft and new prop placement, perhaps you would want to look into a "Kort Nozzle". If that doesn't translate, do a web search you'll find plenty of hits on the theory.

Essentially you are putting the prop in a tube, like a short length of pipe. The downside is additional drag under sail, but since the prop is now turning in a closed tube, it gains some "end plate" effect from the tube, the same way that a sail gains efficiency when it reaches down to the deck. And--there is close to zero pressure bump against the hull, since the water thrown off the prop blades simply is pressing uniformly against the tube, not being thrown up into the hull with each revolution.

Perhaps this is something to look into?

[ernest]

Jose, I am not having any vibration problems emanating from the propeller anymore. In that respect the VolvoPenta folding prop is excellent. The clearance between hull and prop ends are less than 15% and the backend of the hull in front of the propeller is very badly shaped and should create a lot of turbulence. In that aspect I am very pleased with the VolvoPenta. The backing characteristic is however terrible. Prop-walk is the worst I ever experienced so I am happy not have to "park" the boat the mediterreanen way. I just put it nose in between my Y-booms.
My main problem right now is engine noise and I am going to buy a new more powerful engine and together with that I was very interested in an Autoprop so I could really bring down the motor rews under cruising. After reading your and dkall's letter I am not that interested any more. Maybe a Gori or Variprop will suite me better or even a new VolvoPenta if I could stand the prop walk.
Like you I will also have to do a lot of insulating of the engine room.
It is quite large in my boat with large flat panels that really can transmit the engine sound.
Now is however the time for saing in the fantastic archipelago along the Swedish east-coast. You should envy me!
Best regards, Ernest

[ernest]

Hello hellosailor, I have been thinking a lot of a propeller nozzle since my propeller sits very unprotected when I lift my keel. The Southerly has a hydraulically lifted keel which brings down the draft from almost seven feet to only two feet.
The prop becomes however totally unprotected when I am "mud-hauling" into a small bay or other shallow waters.
The prop-walk will go away for sure.
My prop shaft angle is around 10 degrees and I am very concerned how much drag that will create. Do you have any idea? I will follow your advice and surf the web but right now is sailng time!
Best regards,Ernest

[dkall]

To provide a baseline of the Autoprop, it is my experience that if you turn one slowly you will not have any problems. It seems to autopitch as close to square as possible. In the first one they sent me, had I been able to turn it at appro 700 rpm (shaft rpms) I would have been fine. I believe because I had a max of 1300 rpms (again shaft rpms) that caused somewhat of a problem. I don't know if tip clearance has anything to do with prop rpms but that seems to be where most of the issue was.

I'm not ready to give my full attention to the one they sent me yet. I've only used it on one overnight. So far it is much better. It seems quieter and I have approx 1 kt less speed at 1400 rpms (engine rpms). I think it an improvement and am likely to keep it.

So, if I was to repower and get a transmission setup that would turn the prop slower; say under 700 rpm shaft speed, I would seriously consider yet the Autoprop. Why sailboat engines like the higher rpms I don't know and that is yet another thread, I'm reminded that propellors on ships turn awfully slow.....

[jose r vigil]

Dear Ernest


thanks for your reply

Yes I was also attrracted by the possibility of low rev motor sailing with the autoprop but the strong vibratioon started at 1600 rpm. (engine rpm)

If your shaft is hanging down more than 7 degrees I dont think either the autoprop is for you, as per my study about this prop.

i have had a 3 blade volvo on my first sailboat and I was happy. I have used it for 5 years without any problem.

I have been reported in the Hanse forums by a Danish owner that the new 4 blade VOLVO has a vicious port pulling of the steering and they got a switch to a Gori. The problem was resolved.

Before hearing that I would like to buy the Volvo 4 blade but forums are an excellent way to avoid problems before they occur.

I'm not an expert but I dont understand the volvo four blade design. It looked like a low cavitation submarine prop. The blade shape is very unconventional.

To insulate an engine room you have to close any holes and provide fresh air to your diesel via protected cowl vents powered by a fan. Better in the transom and as high as possible. You probably know how.

Thios is quite important as many boat engine rooms get fresh air from the bilge so you can not insulate those engine rooms

Later you need a quiet marine low rpm diesel ( not a marinized whatever) I'm very dissapointed with Yanmar 3800 rpm is too fast to design an efficient prop size/

Good flexible engine mounts are important

An aquadrive or similar double joint bearing if you have a shaft.

And to completely cover the engine room with a double wall sanwich material which is fire rated 0 or 1.

And double rubber bands on door hinges and closings

I'm in the latest step trying to get some insulating matyerial at affordable prices with at least 20 db insulation in low frequencies. I have been asked for 240 USD for every sheet in some places....More expensive than lobster!

If low rev motorsailing appeals you the gori is the only prop as far as I know with double pitch.

Four blades provide a smoother turn ( as they are more balanced) but the efficiency is lower that the three or two blade prop.

Good sailing

Jose

Originally Posted by ernest

Jose, I am not having any vibration problems emanating from the propeller anymore. In that respect the VolvoPenta folding prop is excellent. The clearance between hull and prop ends are less than 15% and the backend of the hull in front of the propeller is very badly shaped and should create a lot of turbulence. In that aspect I am very pleased with the VolvoPenta. The backing characteristic is however terrible. Prop-walk is the worst I ever experienced so I am happy not have to "park" the boat the mediterreanen way. I just put it nose in between my Y-booms.
My main problem right now is engine noise and I am going to buy a new more powerful engine and together with that I was very interested in an Autoprop so I could really bring down the motor rews under cruising. After reading your and dkall's letter I am not that interested any more. Maybe a Gori or Variprop will suite me better or even a new VolvoPenta if I could stand the prop walk.
Like you I will also have to do a lot of insulating of the engine room.
It is quite large in my boat with large flat panels that really can transmit the engine sound.
Now is however the time for saing in the fantastic archipelago along the Swedish east-coast. You should envy me!
Best regards, Ernest

[jose r vigil]

dear hellosailor

thank you



I have never heard of that approach but I have seen it on the yards.

I will search for information as it looks like an interesting issue

Thanks you

Jose

Originally Posted by hellosailor

Jose, if you are going to the trouble of considering a longer shaft and new prop placement, perhaps you would want to look into a "Kort Nozzle". If that doesn't translate, do a web search you'll find plenty of hits on the theory.

Essentially you are putting the prop in a tube, like a short length of pipe. The downside is additional drag under sail, but since the prop is now turning in a closed tube, it gains some "end plate" effect from the tube, the same way that a sail gains efficiency when it reaches down to the deck. And--there is close to zero pressure bump against the hull, since the water thrown off the prop blades simply is pressing uniformly against the tube, not being thrown up into the hull with each revolution.

Perhaps this is something to look into?