Marlow 65' seatrial vibration

This is likely to set off a slew of comments. But I've heard of Marlow vibration issues since their inception. The few that I've ran all vibrated, some owners have spent significant amounts of money at boatyards chasing the issue only to eventually give up. The tab and stabilizers compensating would add to it. There is a reason that no other manufacturers do twin keels in front of the props, clean water flow is important.

This is one reason I advise that you cannot judge any Marlow on the basis of having run an "identical" one, because no two are identical. They constantly have made changes even to existing models, either mad scientist or constant improvement depending on how you feel about them. Therefore, until you sea trial the exact boat, you have no idea. Sometimes you learn as you did this time.

Ok, I too wouldn't touch a Marlow. I ran a brand new 2014 56' once. It too had times when it had a lot of prop cavitation and vibration. Trim tabs and stabilizers generally do not cause vibration. However underwater exhaust does and it's location. Most Lazzara's have a huge problem with this, and Lazzara has come up with a hull modification called a fence to help a lot with it. Its a combination of too little propeller blade tip/tunnel clearance and location of the underwater exhaust too far forward and close to the props on them. I've seen it on a Lazzara where the cavitation was so bad, it was trying to rip the engines right off of the stringers. I'd go straight to a Fleming and never looked back, as I've run an Offshore in the same size range you're looking at and it too had horrible performance issues.

I wouldn't necessarily say random. It's a not uncommon problem that some Marlow's might have and others might not. I'd assume it until a boat proved me wrong.

Of course a Fleming 55 is small beside a Marlow 65. Now a Fleming 65 will feel better although still won't feel as big. Just one huge difference. The Fleming can cruise the world.

If you do a search on YF, I seem to recall a thread from many years ago by someone else who had vibration problems with Marlows? There is also a Fleming vs. Marlow thread with a good number of well-informed posts. Found this in YF's trawler forum...

http://www.yachtforums.com/threads/fleming-or-marlow-yachts.17637/

I ve been running an 84 lazzara for about 6 months now, with the fences, and cavitation or exhaust gases aren't an issue as long as you don't jam the engine control forward. On sea trial the rent a cap hired by the seller did just that and indeed the vibration was horrendous. With the C32s the boat gets in plane at 1500rpm / 17kts and 38% load so i usually add 100rpm every second from 1000 to 1500. 5 second total... common sense

It s like getting into a high performance car, putting the pedal to the metal in first and wondering why the tires are spinning...

Good analogy.

It's a characteristic you've learned to live with, to work around. Now, I don't think the Marlow solution is necessarily as simple.

Yes they're a 2" thick and deep lip they glass halfway around the center side of the exhaust opening and then run back the edge a few feet. Quite honestly I would be looking for another boat. I would be buying a boat with majoring engineering issues from the builder and also poor business ethics from same builder. A 64' Hatteras MY is another option, they're fast some cruise at 28 knots but you can dial them back to 20 knots at 100 gph, or 10-11 knots at 15 gph or so. A lot less exterior maintenance than a Marlow or Fleming. The Offshore I ran was right around the same size as the Marlow you seatrialed.

Some 63' Hatteras MY's were built with C18's. I ran one with them, it still cruised at 24 knots and burned 75 gph.

Here are some pics of the fence on the 84. I may be able to accelerate faster but never do because of passengers and stuff around the boat. I just don't see the need to jam the engine controls forward and stress the drivetrain for no reason.

Boats are all about compromises... while the hatt capt J mentioned handles rough water better, in calm seas we burn 70gph at 20kts instead of 100... and the boat is bigger. Fast cruise is 26kts on 110gph and top speed is 32. And all that with no trim tabs...

Back to the original question, vibration can be tough and expensive to trace...the things you mentioned like bad cutless, inop trim tabs are warning signs of neglect... big red flags