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Marlow 65' seatrial vibration

Discussion in 'Marlow Yacht' started by bayoubud, Mar 8, 2017.

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  1. bayoubud

    bayoubud Senior Member

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    Looks similar to the one we sea trialed, it had twin gens. Deceiving when you look at the center line distance on the engines compared to the stern pic in the yard. They could have went outboard a bit more with the engines. Unless you want a fast cruise those 3406E's are a good engine for that boat if speed is not an issue. Seems we saw around 16 kts cruise, but had a trim tab stuck in down position, which bombed out the sea triaI. Boat was really light on fuel, water, and equipment. No tender . Think the later models went to the C18"s for a faster cruise, but still great inline engines for more room in the ER. They may have kept the engines tighter because of exhaust getting into the tunnels. The underwater exhaust ports are outboard and forward of the tunnels, one of the outlets on each side of transom are probably low rpm exhaust ports, the other two could be for the gens.
  2. olderboater

    olderboater Senior Member

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    Here's an excerpt from another model that shows the tinkering and logic you often see with Marlow.

    She has an additional 200+ gallons in fuel capacity and draws 4" less water due to the innovative design of engines placement and reduced shaft angle which have increased speed by 5% and fuel economy by approximately 10%, increasing her already industry leading performance and range.
    Now understand that's all theoretical, the kind of thing designers hope for but long before proven. That is changing engine placement to impact draft and changing shaft angles to try to impact fuel economy or add a little speed. Squeezing in a little more fuel.

    Now I have no idea what changes were made in the 65's or why particular arrangements, but Marlow never has seemed able or willing to get a model that worked well and stick to it for a while. Sometimes they'd change models, sometimes not. A few years ago you had the 57, 61, and 65 and now the 58, 62, and 66 and how new and improved. More likely you had the 65A, 65B, 65C, 66 progression.

    By comparison we had a Sunseeker Manhattan 65. That wasn't a new boat, but just another version of the 63. 63 was galley down and 65 was galley up. Same hull that had been used for years. We were able to run several before buying. Then finally they decided to redesign and came out with a 66 but that was after riding a design a long time and thinking very carefully about changes they'd make.

    I'm very hesitant over new models of even dependable brands. I like proven models, but with Marlow they're always new models or slightly changed.

    I'd also pay attention to how quickly boats seem to hit the used market. Sure there are those who have a life change or something happen that forces them to sell quickly. However, if a builder introduces a new 80' model and within 2 years half of those built are already on the market, there's a reason. Marlow's biggest single fiasco was the 97E and all three built were quickly on the used market. Two did so rather quietly as they didn't want to lower the value of their own boat. The other one sued.

    There are many other examples. Nordhavn built a 120', during rough times and really over their heads with what they promised. The one and only one quickly was on the used market.

    We have a 44' Riva. The original model had issues but by the time it was relabeled the Rivarama Super, the issues were all resolved and has been wonderful.

    Westport has been criticized by some as being dated at different times. However, we found a lot of comfort in being able to charter multiple boats of a model and have something like the ultimate test drives.

    Doing things the Marlow way is just going to lead to issues and some solutions that work out better in the designers head than in reality.
  3. 993RSR

    993RSR Senior Member

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    There were two Marlow's hauled both having the running gear removed. The tech told me they were replacing the vibration dampers aft of the couplings that failed and let the shaft slip back. Yikes
  4. bayoubud

    bayoubud Senior Member

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    HMMM, first time I've heard that. Might be the results of exhaust getting in tunnels. Our surveyor mention at times seeing the engines moving much more than normal, we assumed because of the exhaust cavitation. We were told by the broker that vibration was to be expected when coming up on plane because of the underwater exhaust.
  5. Capt J

    Capt J Senior Member

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    Lazarra's had this same issue, some added a fence (strake running on the inside to help deflect it). I was on a survey of a 68' that didn't have them and the captain went to get on plane quickly. The engine surveyor got so scared he ran out of the engine room and called for ALL STOP. The engines were vibrating so bad, he was afraid the motors were going to rip off of the stringer. It's not the underwater exhaust, it's the placement of the underwater exhaust. Sunseekers have underwater exhaust and NEVER have this issue or fences.
  6. bayoubud

    bayoubud Senior Member

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    Over time that pulsating thrust could cause various problems with the drive train.
  7. Pascal

    Pascal Senior Member

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    Same thing happened during sea trial on the lazzara 84 I run. The “driver” just slammed the sticks forward resulting in massive cavitation. Complete idiot. Surveyor told him to chill...

    From 1000 I add 100 rpms at a time pausing for about 2 seconds each time. Boat is on plane in no time at 1500 anyway with minimum bow rise so no need to stress the running gear. Boat doesn’t have trim tabs anyway, doesn’t need them.
  8. Capt J

    Capt J Senior Member

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    I've seen a few Lazzara's over the years that have eventually snapped shafts from it over time. Most surveyors cite improper blade tip to hull clearance. Lazarra did it on all of their boats to have as little shaft angle as possible and efficiency (which they are efficient).
  9. Pascal

    Pascal Senior Member

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    Don’t I know that. Port shaft snapped two years ago in the Exumas. Was able to retrieve the wheel a few days later. When we hauled out, the other shaft was cracked too. I think the heavy handed prior captain had something to do with it. Haven’t had any cavitation in four years since.

    efficient they are... 70GPH at 20kts (calm water) is pretty darn good for an 84 footer.
  10. Capt J

    Capt J Senior Member

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    I think rough seas effects them also. I think even on plane and in rough seas at times allows exhaust gasses to get into the tunnels and create cavitation and you might not notice it because of the rough seas.
  11. Pascal

    Pascal Senior Member

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    In quartering seas when the stabs deflect all the way you can hear a groaning noise.
  12. Kapn

    Kapn Member

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    Where are the generators? The early 2000's Marlow I ran had them mounted outboard of the engines. Of course it had stand up engine room height, but the engine room length from bow to stern was short and there was minimal crew cabin. Marlow put all that space up into the cabins where he 'beat the competition'. Of course years later there was a decision on that boat to replace the generators. I asked the next captain how they did it with them being outboard of the engines. He said they stripped them to the block and got them out of the boat with lots of effort. The new ones were installed by stripping them to the block and reassembling them in the engine room. Cost a fortune and the new generator warranty was crumpled up and tossed in a garbage can.
  13. Cowger

    Cowger Member

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    On this 2002 model, they appear to be mounted aft of the engines, at least as shown here on the starboard side. The listing specifies twin 20kW NL, so I'm assuming that the other one is on the port side; no pictures show it, though.
    4.jpg

    I'm planning to step on board this boat next week and should have a better idea of the overall layout then.
  14. bayoubud

    bayoubud Senior Member

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    The 65/70 Marlow's I've seen had twin gens , one aft of each engine. Just inside the er entering from the crew quarters.
  15. Capt Ralph

    Capt Ralph Senior Member

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    Going back to the Marlow I last commented on (#95 above), The gen sets were behind the mains, In boxes, slightly over the shaft logs.
    You could still play half court B Ball in there. That is why I was asking why now, the shafts are so dam close to each other.
  16. Capt Ralph

    Capt Ralph Senior Member

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    On the '04, 71', from post 84 above, still some good room between the mains, the gen set were outboard of the mains and the batteries were ,,, who knows where. Still I felt there some great space between the wheels.
    I got tight on this boat with the owners. Their puppy was an old saint. Sadly he passed a couple of years ago (old age gets us all).
    Now, This dog could tell some stories as he was the one who luved the boat the most.

    Sometimes I do get in sync with boat critters.
    I can not repeat what My kats say but they are happy.
  17. Kapn

    Kapn Member

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    Aft of the engine makes a lot of sense. Looks like good access around it. Why no hush box?
  18. Cowger

    Cowger Member

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    It's a good question. One possible answer is this part of the listing: '3" Lead / Foam Engine Room Insulation' -- perhaps the thinking is that by insulating the whole engine room, it's less important to hush the generators?
  19. Capt Ralph

    Capt Ralph Senior Member

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    Looking at the top picture in post #86, how much shaft is between the cutlass bearings?
  20. Cowger

    Cowger Member

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    Here's the best picture from the listing which would show that:

    5.jpg