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Old 30-01-2023, 19:21   #1
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Sea Trial Result question

35 ft boat
15000 lb
3gm30f 27 hp 3600 rpm
3 blade feathering prop.

During the sea trial, the engine failed to reach full rpm, maybe 3200.

Initially these was some vibration but improved after we scraped off some barnacles. Still seamed excessive to me.

Both the throttle and gear shift levers were reported to be very stiff. Could not verify they were hitting WOT.

Some play was noted in the cutlass bearing.

Surveyor states replace cables, cutlass bearing and exhaust elbow at next haulout.

Our intended use of the boat will entail a good amount of motoring.

Is it reasonable to require these items be corrected prior to purchase or reduce purchase offer accordingly.

Boat yard, over the phone ballpark quote is near $3000.

Replace both cables
Replace cutlass bearing
Replace exhaust elbow
Align engine.
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Old 30-01-2023, 19:47   #2
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Re: Sea Trial Result question

Could be over propped, dirty bottom, over weighted or even some fouls to the prop you missed. WOT and max prop speed are effected by lots of things. If the boats not moving through the water at rated speed; given all the elements, you likely never see rated max rpm. Dirty bottoms and fouled props are probably one of the leading issues that cause spun prop hubs. Especially folding props as they are typically much heavier than stock props. Of course also yanking the gear shifter back n forth without pause will assuredly do it over time. Anyway, just a few thoughts. The engine torque likely has no issues.
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Old 30-01-2023, 19:52   #3
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Re: Sea Trial Result question

Bottom was in very good condition with no barnacles.

Prop:

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Old 30-01-2023, 19:54   #4
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Re: Sea Trial Result question

Me - I would allow the owner to fix and perform the sea trial again if it fails to get full RPM - run away. Dont walk - run away there is more going on than is worth the risk.
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Old 30-01-2023, 20:34   #5
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Re: Sea Trial Result question

Quote:
Is it reasonable to require these items be corrected prior to purchase or reduce purchase offer accordingly.
There are many factors - how is the boat priced, who is the most motivated, etc. In the end, you can ask for what you want but the seller can also refuse or counter. On a $100K boat it might be reasonable to expect a $3K price drop, but maybe less so on a $10K boat.

When we bought, the boats we wanted were being snapped up quickly and we were in a hurry, so we accepted the seller's counter offer of about half what we hoped for. But every situation is different.
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Old 30-01-2023, 20:44   #6
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Re: Sea Trial Result question

Many/most boats do not reach OEM stated max RPM. I would not be overly concerned.

Did you run the boat at WOT for >5-mins?

Cutless bearing - I would seek a credit on this unless it was disclosed. Same with exhaust elbow.

Stiff throttle and gear - more information. A lot of sailboats have lousy/stiff engine controls simply because the shift mechanisms suck and the cable routing is ridiculous. Not sure new cables will suffice but it couldn't hurt. Do make sure the tranny engages properly - biggest issue with stiff cables is tranny is not fully engaged into reverse and/or forward.

As a general premise, on older boats, my gut feel is splitting the repairs is fair. The buyer should not expect new; seller should expect to contribut to remediation of undisclosed defects.
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Old 30-01-2023, 21:52   #7
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Re: Sea Trial Result question

Unless it's otherwise a heck of a deal or the one and only boat you could accept...yeah, push for some sort of relief.

If the owner wants to address the issues and demonstrate it hitting WOT, fine.
If not, expect some sort of reduction in price.

Stiff cables would be an issue no matter what. While it might be poor routing, it's often an indication they are near the end of their life.
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Old 31-01-2023, 00:58   #8
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Re: Sea Trial Result question

As was said, it’s all a function of the price. Owner may have already considered these items. But good to use in your negotiations. Also assume a change in mounts while you’re at it. Btw how qualified is the surveyor with sailboat diesels? My last boat I brought in a separate mechanic to look things over as I questioned the p/o maintenance….. mechanic was spot on and worth the extra few bucks. Also, those items you listed can be easy do it yourself items to shave that estimate.

good luck!
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Old 31-01-2023, 04:49   #9
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Re: Sea Trial Result question

The 3gm30f has one of those stupid 180 mixing elbows. They are a maintenance item, so check if it was replaced per schedule.

To understand this better, Google searched clogged 3gm30f elbows. When they get clogged they create back pressure, or can corrode and spray cooling water into the upcoming exhaust flow. Contrary to the surveyor, I would fix that sooner rather than later.

The other reason could be a prop that is too large. Check the size of the prop versus the manufacturers recommended size.
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Old 31-01-2023, 06:10   #10
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Re: Sea Trial Result question

Quote:
Originally Posted by SV_Galateia View Post
35 ft boat
15000 lb
3gm30f 27 hp 3600 rpm
3 blade feathering prop.

During the sea trial, the engine failed to reach full rpm, maybe 3200.

Initially these was some vibration but improved after we scraped off some barnacles. Still seamed excessive to me.

Both the throttle and gear shift levers were reported to be very stiff. Could not verify they were hitting WOT.

Some play was noted in the cutlass bearing.

Surveyor states replace cables, cutlass bearing and exhaust elbow at next haulout.

Our intended use of the boat will entail a good amount of motoring.

Is it reasonable to require these items be corrected prior to purchase or reduce purchase offer accordingly.

Boat yard, over the phone ballpark quote is near $3000.

Replace both cables
Replace cutlass bearing
Replace exhaust elbow
Align engine.
If you got to 3200 RPM, I'd say that's pretty good. This is a 3400 RPM max continuous engine. As you mentioned the bottom/prop is dirty. Worn Cables is pretty easy to replace assuming its not just a cable brake that is causing the stiffness. My 3GM30F (which I loved) needed a cable clamp on the throttle cable to add stiffness otherwise the governer would constantly push back the throttle to an idle position. Even my 4JH does this needeing some extra friction added to the throttle cable.

Replacing the exhaust elbow on the GM series motos is a regular maintenance thing. Most of theis work is regular maintenance and you can (If you're inclined) easily DIY it. Even the engine alignment is DIY, just takes patience.
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Old 31-01-2023, 07:28   #11
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Re: Sea Trial Result question

Dashboard tachs are not always that accurate. Did you try a photo-tach ?
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Old 31-01-2023, 10:06   #12
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Re: Sea Trial Result question

How was the exhaust? If not black and smokey, and hits hull speed, then no worries except for the maintenance items.
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Old 31-01-2023, 11:33   #13
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Re: Sea Trial Result question

PS:

Does it hit max rpms in neutral?
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Old 31-01-2023, 11:48   #14
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Re: Sea Trial Result question

Quote:
Originally Posted by SV_Galateia View Post
Is it reasonable to require these items be corrected prior to purchase or reduce purchase offer accordingly.

It depends very much on what the sale price is of the boat and on how you have negotiated the deal up to this point.


On the cutless, alignment and control cables:



If this was advertised and presented as a needs-nothing, ready-to-sail boat with all maintenance up to date, selling for say $80,000 or more, and there were no unusual price concessions up to this point then I would think it reasonable to ask for the items to be fixed or an allowance on price to be made.


On the other hand if this is an older boat, a project boat, or a less expensive boat, or if you extracted some price concessions from the seller with the promise that you wouldn't nickel and dime them on the survey results, or if you know there's another offer coming, then it would perhaps not be as reasonable to ask for a concession.


On the inability to reach max RPM


It could be that the tach reads wrong, it could be a throttle linkage problem. Otherwise, this is unlikely to be a readily solvable problem because it would indicate either that the prop is pitched wrong or that the engine isn't developing rated HP. In practice your choices are to take on the risk of a $20,000 engine replacement in the next few years or to walk away from the boat. To some extent this is an inherent risk of boat ownership particularly with older engines. With a newer engines (less than 5000 hours) it may be worth it to get an engine survey but they're expensive and on an older engine they may not tell you anything you don't already know.


Sellers are unlikely to take a material amount off the price for a weak engine because they will instead try to find another buyer who doesn't notice or care. For a day/weekend sailor who only uses the motor to get in and out of the harbor a weak engine can often be nursed along for many years.


Much depends on how good of a deal you're getting on the boat and how much money you're spending.
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Old 31-01-2023, 12:05   #15
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Re: Sea Trial Result question

Note that feathering props can easily have the pitch changed, and the PO may have deliberately over-pitched his in order to run at lower RPM. You can reduce the pitch if you wish.

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