Yet another thruster shear pin post

[Toki]

Here's the deal, my 2016 R27 is out on charter, the rear thruster went out. Motor spins, but no prop action. She comes back next Friday and goes out again Sunday, so I'm lining a mechanic up to fix it on Saturday.

Based on what i'm reading, it's almost certainly a busted shear pin right? Several posts here with great pics and instructions on how to replace it, so I'll line the mechanic up with that info. I'm also going to call FM tomorrow and get the right pin (I'll get a couple, spares would be good).

But here's my question: could it be something other than a shear pin? Are there any other parts I should get just in case it's something else? Is there something that secures the prop that could have failed? We've got one shot to fix this on Saturday, then she's booked solid the rest of the season. I want to make sure I have whatever we need on hand.

Thanks, all thoughts and advice appreciated.

 

[iggy]

Is there any growth in the tunnel or on the prop? Just a thought...........

 

[knotflying]

I would say shear pin. Find out what caused it. Was it the operator or just wear. There isn't anything other than the shaft assembly that can go wrong. A shaft assembly is around $500 so that's a big crap shoot to order in advance. If for some reason that froze up it would cause the pin to shear, but that is unusual to happen

 

[Bobby P.]

I had a dock line go overboard and get eaten by the bowthruster. Pin did not shear. Broke the blade on the bowthruster prop blew the big fuse. You could have a broken blade...

 

[RichBirk]

Hello Dan. Can't help with you'r fix, most likely a shear pin, but you'r problem does bring to mind a possible cause. Many times during the night, while tied to a dock, a lot of debris can build up against the transom under the swim step due to tidal currents. Sometimes difficult to see. I always check under there before pushing away from the dock. Good luck with the fix. Another thought-- I remember during our orientation Andrew saying, don't use the rear thruster while under way in reverse, shear pins can break do to cavitation or propwash

 

[CaspersCruiser]

....Many times during the night, while tied to a dock, a lot of debris can build up against the transom under the swim step due to tidal currents. Sometimes difficult to see. I always check under there before pushing away from the dock.....Another thought-- I remember during our orientation Andrew saying, don't use the rear thruster while under way in reverse, shear pins can break do to cavitation or propwash

Good info. Thanks for sharing it. I’ve never heard the “don’t use rear thruster while in reverse”. I don’t recall I’ve ever done that, but nice to know.

 

[BB marine]

Good info. Thanks for sharing it. I’ve never heard the “don’t use rear thruster while in reverse”. I don’t recall I’ve ever done that, but nice to know.

You can use the stern thruster while in reverse there will be plenty of water and no prop wash. You do not want operate it when underway in forward at speed. There will be disturbed water and prop wash that can cause cavitation and shear a pin.

 

[doke01]

The prop hub is designed to shear/strip as well. Similar to an Alpha 1 Gen II inboard/outboard prop. I haven't had the thruster pin sheer, but I have had the prop strip. This results in the shaft spinning but the prop not. You should check that as well.

 

[Toki]

Thanks Doug, I'll ask FM about that prop shear pin as well. I assume this would need to be done by a diver, or haul out?

 

[scross]

Brian is spot on about this as usual. You do not want to operate the thrusters any time there is a possibility of having air in the thruster tunnel. Air in the thruster tunnel will cause the thruster prop to speed up then suddenly slow down when water comes back. This results in a sudden change in thruster prop speed that will shear the pin.
We have never had a thruster shear pin fail on five years of use. I think it’s because I don’t use the thrusters with more than 1 knot of forward or reverse speed, I try my best to use them on for under 6 seconds at a time and I always wait 2-3 seconds in between directions.
Fingers still crossed every time that I use them trying to be careful following my rules and not have a shear pin failure! Of course a stick hitting the thruster prop is bad news!!

 

[Toki]

OK folks, we picked up a couple shear pins from Ranger, went out to Toki to do the job today. Man. that stern thruster is waaaay down there! I was struggling mightily to get my flabby body down there. Then my wife said "want me to give it a try?". I was thinking, yeah, right dear, if I can't do it, how can you. Then I thought again, she's in terrific shape and very flexible (better be, those gym memberships ain't cheap). Sure enough, she was able to fit her entire body into that aft bench storage, twist her limbs around and get to those two allen head bolts holding the motor on.

OK, enough bragging about my limber healthy wife. The next problem we encountered is than no normal allen wrench will work on those bolts. Not enough clearance. I even had one of those little ratchet doohickies that you stick a bit into, even the bit was too long to get inserted. So, my wife removed her stealthy and flexible body from the compartment, we called it a day and went home. I just got done grinding down an allen wrench so it will work and we're going back tomorrow, when my wife will again contort her lovely and nimble body in there and get the job done.

... which brings me finally to my question in this long winded post. Why the hell did Side-Power use allen head bolts in those locations knowing no tool known to man will work on them. When I put this back together tomorrow, why wouldn't I use simple hex head bolts that I can easily get a common box wrench on? What do you all think?

By the way, have I mentioned my wife's supple and spry body?

 

[scross]

Photos of this marvelous lady are required in your photo album! If I ever have a shear pin failure is she available?

 

[SLyle01]

SOMETIMES Thruster failure seems like the pin sheared BUT isn't: the entire gearleg assembly just FELL OUT of the bow-tunnel during normal docking in our '19 R27 a month ago (it's a low-hour, 1 year old boat!)
LEWMAR's 3 year 'warranty' ONLY covers parts, so I eat the costs for haulout, washdown, tech-exam, removal and replacement labor. PLUS over a MONTH and still no part from Lewmar. The RT Factory & selling Dealer offer little help.
Maybe those with Side-Force thrusters should be glad?

 

[Toucan]

When we bought our 2017 boat, Fluid Motion provided us with a shortened Allen wrench (included with the manuals) for removing and replacing the Side-Power thruster motor screws.

Barry Thompson
TOUCAN, R-27 CLASSIC

 

[sjreib]

Another Question ? I've seen posts about using a stronger stainless steel shear pin. Are those available and if so are you just asking for more trouble and a motor burn out or will a fuse blow which would be a much easier fix than all the crawling around you need to do to replace the pin.

 

[Wee Venture]

Another Question ? I've seen posts about using a stronger stainless steel shear pin. Are those available and if so are you just asking for more trouble and a motor burn out or will a fuse blow which would be a much easier fix than all the crawling around you need to do to replace the pin.

Side Power has converted exclusively to stainless steel shear pins. If you order from Imtra, that is what you will get. The problem with brass is that they would slowly disintegrate with normal use and finally fail.

I don’t know about Lewmar.

John

 

[Toki]

Today my wife got down there with the shortened Allen wrench. Fits fine now, bit she couldn't break the bolts free. I was able to contort upside down and get a hand on the wrench. I applied as much force as I dared, but I didn't want to risk stripping those heads out and turning a simple job into a very complex job. I decided to bag it and leave it to the mechanic. Hopefully he's got tricks up his sleeve for accessing impossible areas and freeing stuck bolts.

 

[Toucan]

Allen wrench socket bolt heads are pretty strong, especially if they are not made of stainless steel. A box wrench or piece of pipe are very handy as leverage tools with short-handled Allen wrenches.

Barry Thompson
TOUCAN, R-27 Classic

 

[JSoup]

I'm writing to say it's not always the shear pin...

A couple of weeks ago I accidentally left our dog leash on the swim platform after taking the dog to shore and back in the dinghy. We motored the hour+ back to our boathouse and left the boat with no issues. I looked for the leash when we got back but figured it must have fallen overboard. The next week our boat partner took the boat out of the slip, anchored downriver and returned to the boathouse, but as he returned to the house he found the stern thruster not working properly. Given it was a hot day, he jumped in after securing the boat and it's not hard to guess what he found wrapped around the rudder and through the stern thruster - the leash. In our case, surprisingly, the shear pin didn't shear, but rather all of the blades sheared from the prop.

Replacing the prop was surprisingly easy, sounds much easier than the shear pin after reading this and other threads. With the help or a friend, two spare props, a spare nut and washer in case I dropped something, and a 13mm socket and wrench taped to a line secured to the boat, we jumped in to tackle the job. It is easy to get under the swimstep with plenty of room to have your head above water but still reach the thruster. After experimenting with blocks of wood to try to hold the prop hub from spinning we finally settled on a pair of channel lock pliers. With my friend holding the hub it was easy to undue the nut and replace the prop, washer and nut - we didn't even drop anything. We did use a dowel to hold the new the prop from spinning. The whole job took about 20 minutes and would be even faster if I even had to do it again.