2001 Grand Alaskan sea trial vibration issue..thoughts?

Didn’t want to side track the thread so I deleted my post asking if it was Yolanda. She's good people. Someone you can trust.

A related thread: Hatteras vs. Grand Alaskan...
https://www.yachtforums.com/threads/hatteras-75-vs-grand-alaskan-78-2003.29909/#post-259089

Usually the cutlass bearings. May look ok if only moving prop manually but should always be done with a long 2x4 board or larger pried on ground beneath prop and used as a pry bar. There should be no movement in cutlass.

I realize I am a little late on this one, but despite me not being a mechanic I have chased vibrations on 2 boats. In my limited experience money given to the right professionals can solve the vibration issues provided the vibrations are a result of drivetrain issues. If the vibrations are coming from exhaust issues creating cavitation or some hull problems or some marlow velocity struts/keels then all bets are off. If the boat is in S Florida and it is determined to be a drivetrain issue I think you have a good chance of solving the problem. To my eyes that rudder is not slightly bent and it is highly likely that that bent rudder is not “lined up” or towed in properly with the other rudder. It makes you think that a hard grounding occurred and if that is so, is there movement in the struts as I would want to check the mounting of the struts and rudders. Next I would do is hire an outfit that does laser alignment. Pull the shafts and send out to check for straightness and start all over irregardless of what the owner said was done. You may have to spend money that you don’t need to unless they find a smoking gun. In others words, replace all engine mounts whether they are known to be a problem or not. I had an occislating shaft that was bothering me and sent videos to my service providers and was told it was misalignment and to keep running. Of course I was in the Bahamas. Fortunately I made the crossing back to florida and my transmission cracked its case. So was the shaft occislating the problem or was the shaft occislating because an internal transmission issue? Any way all of that lead to laser alignment which did result in moving one strut. Now I have a very smooth running boat. My boat is 54’ and the flybridge is 2 decks above the struts and I could never feel it at the helm. So your description of the problem makes it sound significant to say the least. On my previous boat the bore of one of the props was the issue. That of course was the last thing checked. Lastly I realize this is a boat for sale so that complicates things. See if they could give you another sea trial and if accessible put your hands on the strut mounting plates and see if the vibration is isolated to one side. But you might could deduct a significant amount from the purchase price and solve this issue for less (with the right people) but that is a risk. I hope I have helped.

If you get a satisfactory answer to why the rudder is bent and why shafts and wheels were replaced you could then go to next steps. Ask the seller to check some of the easier, less expensive potential causes of vibration to see if it is an easy fix or more involved. Given the extent of vibration explained, the seller should be willing to have the engine alignments checked, the cutlass bearings properly inspected and the motor mounts looked at. Assuming the shafts and props are good due to recent replacement, if alignments, bearings and mounts all check good then there is an issue that is likely to get much more expensive and involved to correct.

Regarding vibration - It's not clear to me if vibration is related to RPM speed, or vessel speed through the water.
Does stopping/reducing power on 1 shaft; while leaving the other WOT, change vibration immediately, or when vessel slows down? And finally, THAT RUDDER! It's not just bent - it's curved. So it's creating "lift" which is creating cavitation.

Lots of good ideas here. To summarize easiest to hardest in my mind. This might just be good ideas for anyone reading this who comes across a vibration and heads back to the dock before checking further.
Run the engines up to speed in neutral one at a time and then both.
Run the boat with the stabilizers centered and depending on the style a second time with them turned off and free flowing. They could be misaligned so they think they are centered and really creating drag/disturbing the water.
Run the boat on one engine and then the other to isolate if it stays with a side.

Then back at the dock schedule someone to look at alignment.
Throw on the bathing suit and check the props for lines or severe damage to the props.
Assuming hauling takes time and money that's the next place I go. Checking props out of the water to make sure a blade isn't forward or backwards a bit, the edges are smooth, cutlass bearings, shafts turn true, etc.
Then pulling off props for reconditioning, pulling shafts, etc.
Then calling someone who specializes in vibrations.

However, for a potential buyer, nothing has changed. The boat's got a significant issue of unknown cause. Might be minor or might be major. I'd put the burden on the seller.

Considering that the seller must be aware of this issue, you would be better off stepping back & working out why the problem was not addressed by the owner before putting such a vessel to market. Whether it is a Grand Alaskan or Grand Banks or Fleming; fact is there is an issue which is serious & has not been resolved by the owner who wishes to sell the boat. I would step back & suggest that the owner resolves the problem before you go through with the purchase. Why would you go ahead & buy into a problem that is not yours? Given that the market is so strong it may be a case where the seller is trying to offload the boat knowing that the problem is difficult to resolve, or costly & hopes that the buyer will compromise.
In any case, you have the choice to say no & move on to find a vessel without these problems, even in a sellers market. Do not put yourself under pressure to buy an obviously attractive boat, but one with problems that may be serious.
Keep in mind; every major issue will mean time where you cannot use the boat. You may be spending months with the vessel on the hard stand. Plus the cost. Do not compromise.

A lot of the Taiwanese tubs have vibration and ill handling characteristics when you push them past hull speed. A cheap build is a cheap product with poor engineering. That and your rudder is clearly bent in the 4th picture. I would run and buy a quality build.

Just don't ever take on someone else's problem unless you're sure you know the solution.

adding my 2cents.......although a well laid out yacht and may fit your needs......i would not walk away from the deal i would RUN

patience is a virtue and good comes to those who do their research not always in a hurry.....plenty of fish in the seas and nice legit yachts afloat that will eventually turn up....cheers

Scott

Run Forrest, run

Some of the visible stuff in that survey like the exhaust issues alone would have stopped me from even going to survey and wasting money.

these are not just scratches on the keel... they re heavy gouges. Wth did they hit??

i m no expert in analyzing oil analysis reports but too many red flags there as well.

and the performance is just awful. This is not even a fast trawler it s a trawler

some of the issues like performance (or lack of) and exhaust leaks point to build quality issues. Others are lack of maintenance and care. Who puts a boat on the market with an overheating generator and cracked leaky exhaust?

there are some things that only a survey will reveal but this is not the case here. I would recommend that you hire a experienced captain to preview the next boat you will put under contract and have him present for a pre survey sea trial. It will cost you a few hundred bucks but could save you thousands in survey costs

Not as a disagreement to any of the above about walking away or putting burden solely on Seller to remedy all major issues prior to further negotiations. But I thought I would mention the following for the benefit of others. I recently read about an oil analysis lab that had erroneous samples due to improper cleaning between samples. I cant find it after a short search. I am older but not demented. I know I read it as that same lab gave me to red flags for elevated copper on both engines. Also while I agree to take samples upon survey I think that one shot samples are subject to a lot of interpretation. I annually sample my oils and have had yellow readings that concerned me only to be told by mechanics to ignore it and keep running. I have been told that Man does not have any specs on iron, copper, etc for oil intervals. I think I am describing that correctly.