Re: [Amel Yacht Owners] sea wather from bow-thruster

James Alton


   I agree, the bow thruster is a really great design.  IMO, it is vastly superior to the tunnel type thrusters due to the larger diameter, slower turning (more efficient,  more thrust).  I also like the fact that when it is retracted everything is protected.  I am hoping that the bottom paint will be pretty effective in controlling marine growth.  With a high speed in tunnel thruster I have found it hard to keep paint on the blades.  Henri Amel had a lot of vision I think.

   I gave the gearbox of my bow thruster a really good flushing with white spirits.  There was a slight amount of milky oil and rust in the very bottom.  I replaced the prop shaft lip seal and refilled with fresh oil but so far I have not replaced the bearings.  The thruster sounds good when run in both directions both before and after the servicing  but I noticed that it felt a little rough when I turned the shaft before the oil was replaced.  With the boat out of the water, the prop takes more than 3 seconds to spin down.   I could not feel any play at all in the prop shaft, laterally or in and out.  I would like to replace the bearings as you suggested but am hoping that I can get another 3 months out of what are probably the originals.  Can you advise based on this information whether you feel I should change them now, or go one more season?

   The foam seals have all been replaced and they have a lot more compression than the old ones.

   Good point about releasing the tension on the halyards.  I actually removed all of the sails for storage so the tension is just enough to control slapping.

   I note that my boat has a powerful adjuster on the main permanent backstay.  Is this to make it easy to add tension to reduce forestay sag or to make detensioning that stay easy when the boat is not sailing?



On Oct 17, 2016, at 1:57 PM, 'Bill & Judy Rouse' yahoogroups@... [amelyachtowners] <amelyachtowners@...> wrote:

Both good questions.

Here is my opinion. Henri Amel created a really good retractable bow thruster when there were none on the market. It went through several changes and updates in its 25+/- year history. I suspect the O ring was replaced by the lip seal for some good reason. I do not know the reason.

I believe and Amel specifies that the bow thruster should be serviced every 2 years, replacing the gear oil, the foam donuts, lip seal, nylon hub for the propeller, and the propeller shaft seal. Your Amel is certainly due for the two year service and also possibly the replacement of the internal bearings. 

I have never stored BeBe on the hard for any length of time, but if I did, it probably makes sense  to release the pin on the Bow Thruster. BTW, Amel recommends releasing tension on all sail halyards when not sailing.

BeBe 387

On Mon, Oct 17, 2016 at 12:24 PM, James Alton lokiyawl2@... [amelyachtowners] <amelyachtowners@...>wrote:


   Great analysis.  

   On the bow thruster for my 1987 Maramu, I have two large O-ring grooves moulded into the hole in the hull for the composite tube to slid and seal on instead of the lip seal used on the Super Maramu.   Do you know if this system worked well or should I look at upgrading to the newer system with the lip seal?

   One other question.  I noticed that the old foam donuts had compressed quite a bit,  measuring about 2/3 of their original thickness where they had been under pressure.  My boat is currently in dry storage and I was wondering if it might be best to leave the pin out and to not fully compress my new seals until the boat is put back into service?  


James Alton

SV Sueno
Maramu #220
Sardinia,  Italy

On Oct 17, 2016, at 10:59 AM, 'Bill & Judy Rouse' yahoogroups@... [amelyachtowners] <> wrote:

This is my guess:

When the "B.T. climbs higher and the pin enters without effort," the foam donuts are probably being distorted and water is passing through where the foam is distorted.

When the "BT climbs less, the pin comes in with more effort," the foam aligns as it should and the unit is sealed.

I believe your problem with water entry is that the "raised limit" is not correct when the "B.T. climbs higher."

There could be different causes based on the year of manufacture of your Amel bow thruster. If I had your problem on Super Maramu #387, the most likely defective parts would be the upper limit switch or the relay it is connect to inside of the control box...and it could be either the switch or the relay, or both. 

I am convinced this is what is happening when  the "B.T. climbs higher and the pin enters without effort:"
  1. The bow thruster goes up and reaches the "raised limit" where it should stop
  2. The "raised limit" switch engages when it should...BUT..
  3. The actuator motor which raises and lowers continues raising the bow thruster until it reaches a physical limitation
  4. The actuator motor strains against the physical limitation and amperage increases in the circuit as the bow thruster can no longer move and heat travels through the circuit.
  5. When the amperage and heat increases enough through the relay, the relay finally makes correct contact or opens, stopping the actuator motor.
  6. But the bow thruster has distorted the lower foam seals and water will enter.
If this is not corrected soon, either some things will burn up including the actuator motor, relay and switch, or a fuse inside the control box will burn...but earlier model bow thrusters did not have this fuse and some bow thrusters have too large of a fuse.

Hopefully with my explanation, you, or a technician can find your problem.

In the meantime and until it is repaired, I advise you to manually turn off the bow thruster when you are raising it before it reaches the physical limit. One person at the bow thruster and one at the bow thruster power switch will work...then use the pin. You may have to pull on one of the cables to align the pin correctly.

BeBe 387

Questa è la mia ipotesi:

Quando l'elica di prua (B.T.) "sale più in alto e il perno entra senza sforzo", le ciambelle schiuma sono probabilmente essere distorti e l'acqua sta attraversando in cui la schiuma è distorta.

Quando "B.T. sale meno, il perno entra con uno sforzo maggiore," la schiuma allinea come dovrebbe e l'unità è sigillata.

Credo che il tuo problema con l'ingresso di acqua è che il "limite sollevato" non è corretto quando il "B.T. sale più in alto."

Ci potrebbero essere diverse cause sulla base dell'anno di costruzione della vostra Amel BT. Se ho avuto il problema su Super Maramu # 387, le parti più probabili difettoso sarebbe l'interruttore di limite superiore o il relè si collegano verso l'interno della scatola di controllo ... e potrebbe essere sia l'interruttore o relè, o entrambi.

Sono convinto che questo è ciò che sta accadendo quando il "B.T. sale più in alto e il perno entra senza sforzo:"
1.) Il B.T. sale e raggiunge il "limite sollevato" dove dovrebbe fermarsi
2.) L'interruttore di "limite sollevato" impegna quando dovrebbe ... MA ..
3.) Il motore attuatore che alza e abbassa continua alzando il B.T. fino a raggiungere una limitazione fisica
4.) Il motore attuatore ceppi contro la limitazione e l'amperaggio fisiche aumenti il ​​circuito con B.T. non può più muoversi e calore viaggia attraverso il circuito.
5.) Quando l'amperaggio e calore aumenta abbastanza attraverso il relè, il relè, infine, rende corretto contatto o si apre, arrestare il motore attuatore.
6.) Ma la B.T. ha distorto i sigilli schiuma bassi e l'acqua entrerà.
Se questo non è corretto presto, sia alcune cose brucerà tra cui il motore attuatore, relè e uno switch o un fusibile all'interno della scatola di controllo brucerà ... ma modello precedente B.T. non ha avuto questo fusibile e alcuni propulsori di prua hanno troppo grande di un fusibile.

Speriamo che con la mia spiegazione, voi, o un tecnico in grado di trovare il vostro problema.

Nel frattempo e fino a quando non viene riparato, vi consiglio di spegnere manualmente il B.T. quando si stanno alzando prima che raggiunga il limite fisico. Una persona alla B.T. e uno al B.T. interruttore di alimentazione funziona ... quindi utilizzare il pin. Potrebbe essere necessario tirare uno dei cavi per allineare correttamente il perno.

On Mon, Oct 17, 2016 at 9:00 AM, rossienio@... [amelyachtowners] <amelyachtowners@...> wrote:

The bow of my boat is very high on the water level and the water enters in the boat only with waves.
I've done the maintenance and replaced 3 foam rings the springtime this year : two foam rings below and one above. Slightly cutting rings below on a side (starboard). The foams are the new ones 29x42x8.
The problem is :
sometimes the B.T. climbs higher and the pin enters without effort, but , in case of waves, the water filters in the boat.
other times the BT climbs less, the pin comes in with more effort and the water does not enter.

How about  putting a third foam ring under??
To relace the rings in natural foam with those in neoprene coul be a solution?
Thanks to all. Regards.
#SN122 Earendil

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