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Old 27-09-2012, 02:20   #1
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Beneteau 49/50 Bow Thruster leak


I have recently completed two passages from Melbourne Australia to Goldcoast (including Sydney Goldcoast offshore race) and Sydney to Melbourne passing through Bass Strait in a US built Beneteau 49 which is from the same mould as the french 50 footer (go figure).

On our return passage we got caught in an unpredicted gale in this shallow Bass Straight, up to 3m swell one way, 1m swell another way and 1.5m seas on top of this and up to 35+knot winds. Swells were close together and there was a hell of a lot of slamming this relatively flat bottom boat down off the swell.

After a day of this we found we had a leak in the bow thruster tube and had to run for cover fearing that the tube would let go and we'd be pointing towards the bottom of the ocean. We sheltered for 3 days at Refuge Cove effected repairs and limped home.

I've built small fibreglass boats (canoes, kayaks) and repaired with fibreglass and epoxy but I was really concerned when I saw the stock Beneteau fitout of the lewmar 185 bowthruster. Two 185mm glass pipes were bonded to the hulls and joined in the centre. The hull join was significant and well performed. The centre join was an apology for boatbuilding - a small patch around the outside (ie inside of the boat) of the tune that was then drilled for the Lewmar to be mounted. (I cannot understand why the tube was joined in any event it should have been a solid tube, preferably kevlar not glass).

With 40 pounds of electric motor suspended on the tube it was no wonder the tube cracked under the pounding it got in the gale.

My question is whether there is any other accounts of this potentially catastrophic failure.

I am aware of a recent loss of another 50 ft beneteau in an Ocean Racing Club of Victoria (a club I am a member of) in unexplained circumstances. Scuttlebut I've heard suggests that this vessel was lost because the boat was sailed with spinnaker sheets attached to spinnaker in the front hatch, which was left unsealed in heavy seas. I doubt a skipper would knowingly do this, and I have definitely seen no official report saying this. But Im just wondering whether the bowthruster tube setup I saw may have contributed to this nearly fatal outing for the 6 POB.

Please respond if you have heard of similar issues


Paul Kenna
Melbourne Docklands

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Old 27-09-2012, 02:28   #2
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Re: Beneteau 49/50 Bow Thruster leak

Is the bowthruster tube not contained within a cassion?

In my boat, the tube is laid up heavily out of Kevlar and presumably would withstand even a torpedo hit, but the drive leg can leak (happened to me). In my boat there is a cassion -- a watertight bulkhead behind the bowthruster tube higher than the waterline. If the drive leg leaks or the tube is damaged, seawater will not come into the bilges.

I though all boats with bowthrusters were built that way? If not, they should be.

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Old 27-09-2012, 06:28   #3
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Re: Beneteau 49/50 Bow Thruster leak

Further to my earlier post I provide a link to the detailed report on the sinking of 50ft Benetau Inception provided by my club ORCV.

Safety News

The club highlights the events that led to the sinking of the Inception but discounts my hypothesis that the bowthruster could have contributed. in their detailed report the following statement was made:

  • There was bow thruster built in at construction, fitted at the forward end of the 'Skipper's cabin'.
o This was an athwartships tunnel, with the motor and impellers fitted at right angles, forming a T, with the motor aligned fore and aft and projecting aft.
o The installation had been modified by fitting a large gel battery on the starboard side below the lower bunk to improve voltage and hence thruster performance.
o This was secured in chocks with two, 2-part webbing strap over the top, tensioned by a plastic webbing friction buckle.
o It is surmised that the webbing could have come loose under repeated tensioning as the boat worked in a seaway.
o If so, the battery was close enough to have become a battering ram and damaged the bow thruster integrity.
o The inquiry heard an anecdotal account of another yacht suffering from flooding when the unsupported bow thruster motor worked in a seaway, inducing a fatigue failure in the casing leading to flooding.
o Water coming in through a damaged bow thruster would have been fairly confined to the 'skipper's cabin', as it could only pass into the boat via the limber holes in the bulkhead, which was otherwise fairly water tight - eg cable looms were dressed in with sealer.
The deck hatch was the only entrance to the 'Skipper's cabin'.
o It was possible that the hatch worked in the seaway and allowed
water into this compartment.
o The hatch opened forward, ie the hinges were on the aft side.
Water in the Skipper’s cabin had previously drained away, so it is assumed there were limber holes to the main bilge.
o These had not been sighted so their existence is surmise and status unknown.

Now the layout of this 50 footer was different to the 3 cabin Benetau I was sailing in. I and my wife had the privilege luxury front berth cabin (funny how the rest of the crew gave us this opportunity) - the skippers cabin layout was a two pipecot space that included our spinnaker hatch as well as the near forepeak. I disagree with the enquirys conclusion that the water wouldnt flow backwards through the limber holes to the bilge pump - we saw a lot of water movement as a result of the break of the bowthruster tunnel

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Old 07-10-2012, 03:25   #4
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Re: Beneteau 49/50 Bow Thruster leak

I thought I'd copy this in case anyone else has the lewmar bowthruster.

We've had the boat on the hardstand for a week now and have thoroughly repaired the tube after haveing a naval engineer and inquiry members from ORCV inspect the poor standard of manufacture. The tube was a spiral wound "exhaust" tube not a proper bowthruster tube. It should never have been uses in this factory oem bowthruster.

Refer attached the following article about the same tube used on a different vessel which Lewmar were happy to use but the repairer refused.

Bow Thruster Issue :: Tommy Solomon Yacht Repair & Restoration

Lewmar Exhaust Tube for Bow Thruster Tube Issue in Tartan 3700
As of 2009 (Bow Thrusters of North America) was formed to accommodate those requiring bow/stern thruster installations with guaranteed workmanship.
Before reading, please keep in mind this was published mid to late summer of 07. Also keep in mind this refers to Lewmar tubes. Boat manufacture can be any make, but do have issue with one manufacturer questioning OEM use specifications.

I am a yacht restorer and repair facility located in Annapolis Maryland. During late summer of 07, I encountered a problem with exhaust tube in place for bow thruster tube when contracted for replacement in a Tartan 3700 located at Carr’s Creek Marina in Annapolis, Maryland. A moral dilemma of a certain company wishing to replace factory installed exhaust tube … with same, passing for bow thruster tube. I am compelled to share this with others as a point made over the years by many boaters expressing unfair practice in the marine market place today. My point, exhaust tube is an incorrect application for bow thruster tube and should be looked at closely!

For those not in the know, exhaust tube is of a circular wound glass fiber not able to handle torque bow thruster motors deliver. Aside from not coated with gel-coat on inside of tube, (waterside of tube) exhaust tube is of smaller size and a lesser grade construction not designed for bow thruster tube application. Note the, "Limited Warranty and Key Terms of Supply by Lewmar", a. use of a product in an application for which it was not designed or intended.

True bow thruster tube shall be of a +/- 45° GRP lay-up schedule providing sheer, tensile, and axial strength with gel-coat on ID (Inside Diameter) of tube akin to what one would find in a Vetus bow thruster tube. This gel-coating such as on bottom of a boat hull, protects raw faced resin-glass from water intrusion, etc. Again, not found on exhaust tube. Mainly, my argument lies with the tube being used in this Tartan, installed from factory, and not of being of suitable for use. Also, the customer waiting for months while two different company’s argued to see who was going to pay for replacement as the boat sat on the hard for this entire time. To date, 4/27/08, I have received many contacts from those of you asking, which is the correct tube to be using. If you have a tube constructed akin to that of the Vetus tube lay-up schedule, you should be safe from the alternative.

I have refused to install replacement tube after a day’s work removing cracked Lewmar exhaust tube from this Tartan 3700. When notifying persons contracting me for tube install, explaining exhaust tube was delivered rather than thruster tube, I was directed to a customer service representative for more information. After explaining my suggestion of ill suited equipment sent for this application, I asked manufacture to send a disclaimer for install reliving me from any and all liability for this incorrect install. Knowing I would not install replacement tube, to my surprise the following morning a disclaimer was E-mailed to me. My goal and attempts driven by my curiosity to see if ethics would prevail in a potential dangerous situation as I have here. Unfortunately this was not to be, read further.

This is the actual text delivered to me by E-mail 8/16/07, 9:04AM:
FYI, I have attached a copy of our warranty statement to this email.
Lewmar takes complete responsibility in regards to the quality of the thruster tube, in and of itself, that we have asked you to install.
If the tube breaks again and it is proven to be an issue with the quality of the tube you are not liable for any damages regarding the tube itself.
That being said, Lewmar is not to be held responsible for installation or problems caused by the structural integrity of the boat.
Please let me know if you have any questions,

Joshua McAnany
Customer Service Specialist
Lewmar Marine, Inc.
Phone: (800)362-7212 x202
FAX: (203)453-5669
I am hopeful Lewmar and Tartan has a change in heart and will step up and do the right thing and not just for monetary reasons! However, if you can pick apart disclaimer above, I really have no protection at all in Lewmar’s provision. Setting aside all this, what’s it say when a company attempts to relive a contactor for liability for installing equipment not designed for the job?

Please allow me to continue. If you have ever picked up a thruster motor, you would notice it is of substantial weight and awkwardness. Torque this motor provides coupled with added water drag increases (torque) on bolt fastening points on tube. Look closely at breaking points on tube in my pictures: all at the through-bolt hole areas! Now look at how it has failed. Almost in a circular motion, the same direction of its glass wrap.

Pictures of exhaust tube will also show a repair done one time prior. Note darker cracked areas, this shows several cracks in this tube existed for some time. Note the home-grade silicone repair. Silicone has no business in this application for a repair. Besides, silicones has no adhesive qualities and rarely use this stuff if ever at all. Also, pay close attention to the first three words on tubes sticker sent by Lewmar, "Marine Muffler Corporation…". The word muffler indicates this is a muffler tube, not a bow thruster tube! Some have argued the sticker only indicates this tube is made by a particular company which makes many other kind of tubes. I respectful disagree as it plain for me to see this tube was not of proper construction for the application for which it was used.

If you would like to know a quick way of seeing if you have exhaust tube, verses bow thruster tube, note the "wrap" or "wounding" of glass-fibers (strands) on an exposed part of tube from inside the boat. If you can see a +/- 45° wrap in GRP fibers, most times a red line indicator going in one direction or the other, more than likely you have a thruster tube. If on the other hand you can see something akin to a circular wrap/wound in glass and somewhat thin in nature, you may not have thruster tube. If you know what matt glass looks like, see how close it resembles your tube and you may have found answers.

With so many in the marine industry today trying to make money from work not performed, customers not getting what they have purchased, and over all unethical standards with the few, I want boaters to realize even the big company’s will subscribe to unethical practices and anything to save a buck. The cost difference between exhaust tube and bow thruster tube is not enough to jeopardize the safety of any boater and its passengers! For the price of a Vetus tube, say around 4 foot, you can get 10 foot of exhaust tube. I don’t think this small savings is worth the potential problems one may encounter if a dock or lift is not close by.

Two people, one in San Diego, California, and one in Europe, had failures, which could have caused loss of life. Thanks to the travel lift operator in San Diego on his day off and just happen to be standing close by, saved this boat from sinking in the channel. The people in Europe experienced failure at sea as water shot up from under the mattress in the V birth. I would beg of anyone with more connections than I to assist me in getting something done soon. One day the unspeakable will happen causing a terrible situation. Its just a matter of time!

I am sure I will get some heat from this and welcome every bit of it! Nevertheless, I will not keep quiet about something so blatant as this and beg for someone to challenge me on this!

My goal is to see the customer use the boat safely with no added concerns of equipment failure.

Click here to see pictures of the issue

Regards, and be well,
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