Bowthruster - workarounds for leaking outer compression seals


David Vogel
 

Hi Colin,

Nice to hear for you, and good to see you’re still active on the forum.

Thanks for that tip. Wish we’d known about that, as we started taking water through the bow-thruster seal on the passage Tahiti – Fiji in a 30G45 type night with largish and very confused seas. The problem with the Bowthruster seals was not totally unexpected, but the quantity of water was alarming at the worst of it. And then it didn’t stop when we regained less challenging conditions.

Our temporary solution, that is still in use, is to remove the metal pin, and then manually re-tension the lifting stainless steel wire with a short piece of line from the lifting wire and tied off to the wooden cross-member at the aft (open) end of the Bowthruster compartment. This lifts the BT motor by about 1cm, which re-compresses the external seals and, voila, problem solved, at least for the time being. But I like your idea too. Please clarify. Is the whole rubber strip wrapped around the 60mm tube, down at the bottom where it passes through the hull (next to the neoprene seal that gets squeezed when the Bowthruster is in the down position)?

Point for future reference: we have been out there and doing it for 4 almost years since our last bow-thruster service. Yes, we should have done it when we last hauled out, but it was well less than 2 years since the previous bow-thruster service at that time, and all appeared to be perfect so back then it was a case of “If it ain’t broke, don’t fix it”. But then, COVID put a year’s dent in the maintenance schedule …

… anyway, I have recently read somewhere else but, to re-iterate, when-ever at anchor (in smooth waters) or especially in the marina, it may pay to “pull the pin” and ease the bow-thruster down a centimetre or two, to take the pressure off the neoprene seals. Leaving the Bowthruster up-and-locked and the seals compressed for extended periods no doubt contributed to the water ingress that we experienced.

Best,

David
SM#396, Perigee
Whangarei, New Zealand


From: <main@AmelYachtOwners.groups.io> on behalf of Colin - ex SV Island Pearl <colin.d.streeter@gmail.com>
Reply-To: <main@AmelYachtOwners.groups.io>
Date: Tuesday, 7 December 2021 at 4:01 pm
To: <main@amelyachtowners.groups.io>
Subject: Re: [AmelYachtOwners] Bowthruster - hex-nut securing he motor to down-tube is stripped out

Hi David

Nice to see you guys are slowly progressing closer to home. Congrats on your trip so far since we last shared drinks together on Island Pearl in Panama. We look forward to seeing you guys back in Brisbane someday.

I do not have a solution for your problem, so best wait for the smarter engineer folks to wake up in Europe & the USA with good answers to this, which I am sure will not be too hard.

The reason for this note is a suggestion ..... Go down to a local bicycle shop near you and purchase a new rubber inner tube for a large and as broad as a possible bicycle wheel. Take this, cut it across to make a long tube, then cut a slit all the way up through it to form a new long, broad single layer of rubber. Always keep this on board to wrap tightly around the base of your thruster if ever you see any leaks there in the future. It works perfectly and even with a badly damaged seal if that occurs at anytime whilst out cruising. In such an emergency it will keep every drop of water out! 

We did this in the Indian Ocean after replacing our bow thruster in the Maldives. At the time we did this in-water, and Amel sent a complete new bow thruster out from France but did not send us a new top rubber ring (the one inside the boat) and hence, although we never ever got water in there at any other time ever, between Chagos and Rodrigues we had huge 6m seas and winds and extreme conditions and en route found about 1 liter per day of seawater getting into the front bilge on that trip. All I could come up with in Rodrigues was this primitive bicycle-type solution, but it worked a treat, and we never had another single drop of seawater till reaching Durban where we were able to lift the boat for all her two-year maintenance, including replacing that all-important top seal. In fact, this system worked so well that it became my standard practice for us to wrap it around that base area of our bow thruster just after leaving the harbor on each and every ocean crossing thereafter "just in case"!  Of course, for all local, Caribbean, and Pacific Country cruising we never put it on, but for long crossings, it was a wonderful comfort to have handy.

Best regards to you both
Colin 
ex Island Pearl II
Brisbane

On Tue, Dec 7, 2021 at 11:10 AM David Vogel <david.vogel@westnet.com.au> wrote:
Greetings fellow Amelians,

Requesting help with a 'small' problem.  After an extended service interval (>3-years since last service of the Bowthuster by AMEL MQ, the unwanted delay due to cruising French Polynesia in COVID times, closed borders, and so on), we're now securely in NZ, primarily for the purposes of attending to long-overdue rounds of routine maintenance - including as a high priority the Bowthruster and C-Drive.

Three of the four 6mm hex-bolts that secure the bowthruster motor to the fiberglass (?) torque-tube have been removed without undue problems - desite some rust clearly evident (due I think to the aging neoprene compression seals) with just the regular tightness as expected, but overcome with normal force of a 15cm shifter (no heat or penetrating oil needed).

Unfortunately, the fourth bolt - the starboard-hand one oriented forward - was found to be almost completely stripped, and the limited attempt to shift it finished the job.   It now presents a round hole, which provides no ability to use an Allen key (either 6mm, or the next size up in imperial) to gain the necessary purchase.  The forward-facing location presents  challenges in terms of access needed to drill and tap in an "Easy Out".  Without drilling, the easy-out can not be inserted far enough to gain any useful purchase.  I have applied heat (MAP//Pro torch) as close as possible to the nut head.  I am also soaking the joint (and the whole motor-tube interface area) with PB Blaster (now also anticipating problems with dropping the tube away from the motor assembly).

Has anyone faced this problem with a rounded hex-bolt before, and found a solution?

Or are there any other tips and trick, hints or suggestions?

Thanking you in anticipation, and with kind regards,

David
SM#396, Perigee
On-the-hard, Riverside Drive Marina
Whangarei, New Zealand







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Colin Streeter
0411 016 445