Re: [Amel Yacht Owners] Hurth Transmissions freewheeling folding prop

David Wallace


I really appreciate your sending the testing procedure (I received that separately, thanks!). We will be hauling in Jan or Feb for bottom painting so the opportunity is at hand to check the continuity. We do keep track of the condition of the rudder zincs, and do have a zinc on the shaft, as well as on the MaxProp. As a side note, in 2007 when we had the engine out for a rebuild I pulled the shaft for inspection. There was no corrosion but some scoring so replaced it given the opportunity to do so easily.

Thanks again for your help. You continue to be a truly excellent resource for all of us Amel owners!

Dave Wallace
s/v Air Ops
Maramu #104
Puerto Escondido, BCS, Mx

On Dec 19, 2017, at 6:11 AM, 'Bill & Judy Rouse' yahoogroups@... [amelyachtowners] <amelyachtowners@...> wrote:


It sounds like you have a bonding problem which may cause you serious issues. I am going to send you a page out of my book which will allow you to test the bonding of the engine to the zincs when in the water. 

Every owner should check continuity between the prop and the zincs each time you haul out. Using the resistance setting on a multitester with a long piece of wire to extend one probe to the the prop with the other probe on the zinc, the multitester should read very little to zero other words there should be close to 100% continuity. 

If there is continuity, you can be assured that your rudder post, prop, C-Drive or shaft, transmission, and engine are protected. Of course, this assumes that everything between your prop and engine are connected metal-to-metal.

CW Bill Rouse
Admiral, Texas Navy
Commander Emeritus
Amel School
720 Winnie St
Galveston Island, TX 77550
+1(832) 380-4970


On Dec 18, 2017 18:32, "David Wallace svairops@... [amelyachtowners]" <amelyachtowners@...> wrote:


Our Hurth 250 started acting up in 2002 with about 6000 hours on the engine. Intermittently it would not go into forward, first discovered when backing out of a slip which made for an interesting evolution. We had it rebuilt with no issue.

Maybe I have a grounding problem on the 4.154 but the aluminum cooler only seems to last a year or two. I now have several, and try to catch the corrosion before it gets to bad. Then I clean up the cooler and rebuild it with aluminum epoxy that I buy from Cotronics. Works really well.


s/v Air Ops
Maramu #104

On Dec 18, 2017, at 7:50 AM, James Alton lokiyawl2@... [amelyachtowners] <> wrote:


   My Maramu has a plate mounted just in front of the shift lever warning to never leave the transmission in Fwd. gear while sailing.  My boat has a fixed 20” (?) 3 blade prop which can produce a large amount of torque when sailing at higher speeds.  I am guessing that since your prop feathers(so produces little torque if any when feathered)  that it may not matter as much which gear you use but apparently due to the design the Reverse gear is stronger and therefore safer to use when locking the prop shaft.  Perhaps others can verify if this would be correct.

   I also read in Foley the these gears seem to last about 1000 hours on average.  The gear on my boat has the same paint as the engine and I don’t see any evidence of it having been replaced.  The engine now has just over 4,000 hours.  Could others comment on the life expectancy the have experienced with the Hurth gears?  My boat appears to have had an aluminum cooler for a very long time,  it may in fact have been original based on the installation.  I replaced the old cooler with a new aluminum one.  The old one was not leaking but when cleaning out the inside I found several pin holes that were only plugged with corrosion so it was overdue.  I just got an email back from Foley saying that they have discontinued selling the stainless coolers and now only sell the aluminum.  I wonder if there were corrosion concerns betwee the aluminum gear case and the stainless coolers.  I will try to find out. 


SV Sueno,  Maramu #220

On Dec 18, 2017, at 11:19 AM, 'Mike Ondra' mdondra@... [amelyachtowners] <> wrote:

Who’d of thought there was so much to know about transmissions and their lubrication! Foley website full of interesting information. On a related topic.


Dr. Diesel Tip #101 at Foley says DO NOT put Hurth trans into forward to stop freewheeling, only reverse.

We have always put the trans in forward to stop the freewheeling and fold the Autoprop when under sail. Given Amels have a “C” drive, does Dr. Diesels Tip apply? Have to pose the question just in case there are opinions among our ranks.


Mike Ondra

Aletes SM#240

Falmouth Harbor, Antigua


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