Re: Bow thruster seals

eric freedman <kimberlite@...>

Hi Jose,

What is your email address?

Fair Winds


Kimberlite Amel Super Maramu #376



From: [] On Behalf Of Jose Venegas via Groups.Io
Sent: Thursday, June 13, 2019 1:32 PM
Subject: Re: [AmelYachtOwners] Bow thruster seals


I understand very well how the system SHOULD work and, if everything is new, the seals should work as designed.  Unfortunately, wear can change the system and, in my case nothing worked to stop the leak, including several adjustments of cable tension, and increasing compression by the pin.  As I said in my previous e-mails, I believe the problem occurs because the wear of the surfaces between the hull and the thruster that guide its motion result in a misalignment between the trunk and the seal, causing a lateral force on the lip seal which makes it incompetent allowing water intake.  The misalignment also results in the sealing surfaces between the donut seals and the hull are no longer parallel affecting its sealing action.   Following Amel instructions and wasting seals, money and time I realized that the problem could be corrected by designing a seal that would be made of a softer material and have lips that could maintain the seal in the presence of misalignment.   That solved the problem 3 years ago and I have had a dry bilge ever since.!!
In my design, I used two seals in series: a silicone wiper below and a silicone u-cup on top. This results in a slight protrusion of the seal above the horizontal fiberglass surface, as it can be seen in the pix I sent before.    I used silicone glue to secure the seals in place and was planning to add washers to secure them to the fiberglass, but after several months of procrastination, I realized that the glue was sufficient to keep the seals in place.  3 years later, using the thruster twice per week, almost every week during 6 months each summer, including a Marion to Bermuda race the seals are still working as new.  Since I add silicone grease to the trunk every year and, given the number of times (~50/year) that I use the thruster,   I am expecting that they will last a very long time.  So far I have serviced the thruster every year but have decided not to change any of the seals, including the donut seals, which looked in excellent condition.

I just received the quote from the seal manufacturer and it is as follows:

10 pcs. Silicone wiper $ 31.65ea.

10 pcs. Silicone u-cup  $ 32.50ea.

This it will be about $65 per set plus shipment and It will take  14-17 business days to ship from the order

so far I have received requests from:

Bob Ross, sv Nomad, Trinidad (1 set) 
Ian and Judy, Pen Azen, SM 302, Greece (?sets)
Chuck_Kim_Joy (? sets)

Steve Davis Aloha SM72  Ko Olina, Hawaii (? sets)
Mark, Cream Puff - SM2K - #275 (? sets)
Dan Taylor (2 sets)

Gerald Bassin Jetlag, SM113 (2 sets)

Since I want to place the order this week I will appreciate if each of you can e-mail me directly with your e-mail, the number of sets you want and the address two where it should be shipped.   
We still need to figure out the cost of shipping to each one of you and how you will transfer me the money, but given that is something we can figure out later.

Ipanema SM2k 278, Boston

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