Weak shafts on 2004 340 Sundancer

ras737

Member
Feb 7, 2010
32
Westerly,RI
Boat Info
2008 44 Sundancer
Engines
Cummins
Please help! I have a 2004 340 Sundancer with the 8.1L Mercs. Last summer I snapped my starboard shaft right at the taper. This was the result of metal fatigue. Apparently this is a common problem with boats equipped with the 8.1L engines because of the higher torque. Also Sea Ray uses Aquanet 19 shafts as opposed to the stronger Aquanet 22. This set me back $4500. My question is what to do with my port shaft. Here are my choices.
1. Do nothing and take my chances and possibly loose another $1800 prop.
2. Have the shaft removed and tested with dye. Cost about $800. Only sees stress cracks on surface and does not guarantee it's integrity.
3. Have shaft replaced cost $2000.
I appreciate any advice you might have.
 
Why did it cost you $4500? That type of failure is most often covered by insurance. BTW @ $1800 I would expect a prop for a 340 would be gold plated.
 
Please help! I have a 2004 340 Sundancer with the 8.1L Mercs. Last summer I snapped my starboard shaft right at the taper. This was the result of metal fatigue. Apparently this is a common problem with boats equipped with the 8.1L engines because of the higher torque. Also Sea Ray uses Aquanet 19 shafts as opposed to the stronger Aquanet 22. This set me back $4500. My question is what to do with my port shaft. Here are my choices.
1. Do nothing and take my chances and possibly loose another $1800 prop.
2. Have the shaft removed and tested with dye. Cost about $800. Only sees stress cracks on surface and does not guarantee it's integrity.
3. Have shaft replaced cost $2000.
I appreciate any advice you might have.
I have a 2002 340 Sundancer with the 8.1L mercs and this is the first I have heard of this issue. How many hours did you have on those shafts before the failure? From a purely numbers standpoint, it seems it would make more sense to replace the shaft for 2,000 rather than spend 800 only to have it tested. Either that, or you save the 800 and wait for the failure and then apply that 800 to the 2,000 cost at that point. If you spend 800 and it shows it has an issue, then you have to spend the 2,000 anyway so you just increased your cost by 40%! Rob
 
Why did it cost you $4500? That type of failure is most often covered by insurance. BTW @ $1800 I would expect a prop for a 340 would be gold plated.

Shaft -$1200
Prop -$2000
haulout- $400
labor- $850
freight and hardware- $100

This stuff adds up when a boat yard or dealer does the work ….them boat owner has few options since he is prop-less on one side.
 
New shaft and sleep well before your long trips.
 
Please help! I have a 2004 340 Sundancer with the 8.1L Mercs. Last summer I snapped my starboard shaft right at the taper. This was the result of metal fatigue. Apparently this is a common problem with boats equipped with the 8.1L engines because of the higher torque.

I respectfully disagree. The 340 runs 1 1/2" shafts as does the 8.1 equipped 360, 380, 40, etc. There seems to be something about the 340's that does not affect the others in the same way. It has been discussed here before, and I think that it came down to the opinion that the harmonics and the vibration and whip patterns of that length of shaft in that boat are less forgiving to misalignment, improper prop installations and imbalance from shaft anodes etc. than the others. A search here may turn up some of those threads. Good luck
 
Actually, I know of qty. 3 40' Sundancers that snapped shafts as well all at one dealership here in FL so the problem is not isolated to just the 34. One of them was in the Bahamas when it went south (or should I say down) and put a huge gouge in the hull when it came off.
 
I had the same happen to me 2012 for unknown reason. This shaft problem has occurred to several boats in my marina, all different sizes, but all 8.1's and similar size shafts in the 04-07 time frame. Try contacting Searay.
 
Certainly other boats besides 340's have experienced shaft breakage, but the consensus was that it is more common in the 340 for some reason.
I think the idea is to be sure that the alignment is checked, and the prop installation done carefully, and everything operates very smoothly. I am often surprised when I ride on other boats that vibrate like crazy and the owners think that is normal because it "has always been like that".
At least I hope that is the case, because if an 8.1 will snap 1 1/2" shafts from brute force, then my 1 3/4" shafts don't have a chance hooked to those cummins.
 
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I've seen allot of these shafts snap on the 340's and 380's but mostly on the 340's. Searay has a collar that you install on the shaft in front of the tide seal so the shaft doesn't slide back and hit the rudder. Obviously it doesn't help when the shaft snaps at the prop side. After I install a new shaft I always see the alignment is way out.

Another thing I see with these models especially the 340's is the tides seals leaking. When I pull the shafts to install the new seals the shaft is very badly grooved from where the tides was sitting
 
Thank you for your input. I bought this boat new in 04 and I am obsessed with keeping it in impeccable condition. My props are sent out every few years to be reconditioned and balanced. My mechanic checks the shaft alignment every spring. I would never run my boat with any vibration. I have a friend who had a 2006 340 who had the same issue a few seasons ago with 250 hours. I considered it a fluke until it happened to me the following season and decided to research the issue. I have 600 hours on my engines so I guess I can consider myself lucky. I suspect Sea Ray knows of the issue but they will never admit it. I am out of warranty so I am on my own. Insurance does not cover mechanical issues. At this point it does not seem cost effective to have the port shaft tested. So my choices are do nothing and take my chances or spend big money to have the port shaft replaced. This is one of the toughest decisions I have had to make.
 
I guess it happens, I just lost a shaft at the taper that was two years old. My boat is 37 years old and this has never happen before. I am wondering if it is poor workmanship, softer stainless or?
 
Time to get out the popcorn and a chair :),Raz you have no idea what your talking about. The insurance Companies don't send the shafts out, would cost way too much for shipping, analyzed etc to prove what? Bad shaft ? There is no way they can tell what would cause it to snap,
 
Sporters 78 with all due respect I do know what I am talking about because I've been down this road last summer and the Insurance co. sent down a suveyor and had the shaft sent to a lab in Mass. It came back as failure due to metal fatigue and denied my claim that I hit an object! I then threatend them with legal action and they could not have cared less. I will be happy to show you there report if you like.
 
I might suggest that if the shaft broke at the end of the keyway on the taper, that breakage may be caused by improper shift technique. If you accidentally shift while the rpms are anything above idle, and fail to pause slightly in neutral, the wheel is still spinning one way while the shaft is trying to go the other way.

That is a good way to snap a shaft.
 
Raz,
for an insurance co to spend $ on a shaft that cost 1200 or so ,is just crazy on there part. Maybe you need a better insurance company. Must be more to your story then you are saying. I have had two replaced no problems with insurance at all.
 

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