Questionable survey?

[SteveK]

STB, I will echo your post.
What do people worry that a full RPM test will break?

WOT is what the maker determined the max RPM an engine should/could run, right? I am sure if something is wrong the engine will spin faster than rated RPM @ WOT. I am also sure if you are overpropped and run at full rpm it will not be reach rated WOT.

Me, I will run up to WOT after bottom is cleaned, I will on occasion attempt WOT to gauge if the bottom needs cleaning. All the while I listen to the engine and watch the gauges.

Why do spec sheets say max RPM if it should not be run at that max RPM? Should it be run at MAX rpm continuous, NO, but not because it cannot. Engines have a sweet spot for max efficiency and WOT is not it.

 

[Fleming]

A short run at WOT is an important prerequisite for me. 3 important reasons. One is to determine if it's properly propped and able to turn up the rated RPM. 2 & 3 are that lots of poorly maintained engines can run fine at cruising speed but turn it up to its rated RPM and that's when you find out that the cooling system or the fuel system aren't up to par.

If a seller is scared to run his engine at its rated RPM, fine, I won't ignore the boat but my offer would be based on needing an overhaul or repower. If the current owner doesn't trust it why should I?

 

[jleonard]

I ran at WOT many times each season, to make sure sll was ok with engine, drive train, prop. Would make sure temperature stabilized, usually around 195 F, would check smoke amount and color.
I would run 1 to 3 minutes as i was approaching home dock.
When i sold the Albin I voluntarily ran it it up with buyer aboard because i had confidence in my systems and maintenance. That 37 year old diesel with 4700 hours ran perfectly.
And at 8.3 knots it was exhilarating lol.

 

[Fleming]

To the question of the decks in the original post, there are two distinct issues with cored decks. There can be moisture in the core, and there can be delamination. Lots of decks can go a pretty good time with moisture before they delaminate. Moisture alone doesn't mean the deck is bad, it can still be solid and percussion sound well. Depending on the type of core it will eventually delaminate, but it might be one year away or it might be 20 years down the road. Very few 30 year old boats have completely dry decks.

 

[STB]

I guess in my thinking, the test is to run up RPMs until reaching WOT or finding a limit...wont go higher...surges...temps too high, black smoke, blue smoke, vibration, etc, and then stopping.

Then the buyers and sellers can have a meeting of the minds...it runs like new....or the cooling system needs service...or the motor mounts or alignment or bearings or props need attention....or it is over propped or shows some age...or there is a turbo seal leak or worn rings or valve seal.concern...or fuel is limited...etc.

I guess to me the test is to run up until there is reason not to. And I just don't see the risk to finding a limit and then backing down.

 

[psneeld]

To the question of the decks in the original post, there are two distinct issues with cored decks. There can be moisture in the core, and there can be delamination. Lots of decks can go a pretty good time with moisture before they delaminate. Moisture alone doesn't mean the deck is bad, it can still be solid and percussion sound well. Depending on the type of core it will eventually delaminate, but it might be one year away or it might be 20 years down the road. Very few 30 year old boats have completely dry decks.

These are NOT cored decks.... They were thick teak plywood with a very thin layer of glass on top...then a screwed down teak deck on top. Lots of leaks into the plywood after so many years. The cabin sides were also just teak plywood with a VERY thin glass coat on the outer side and 4 ply Teak finish veneer on the inside.

The plywood in the deck was very wet but after 24 years after build they were still solid and the glass on top was not delaminating, except one small spot that I fixed.

I might be more picky about engines if they were $50-60K...but drop in rebuilt 120 Lehmans I have seen go for between $7000 and $12,000. I think some of the most solid part of the WOT discussion on either side is engine replace or major repair cost compared to total purchase price and just how old and tired they are.

 

[STB]

I might be more picky about engines if they were $50-60K...but drop in rebuilt 120 Lehmans I have seen go for between $7000 and $12,000. I think some of the most solid part of the WOT discussion on either side is engine replace or major repair cost compared to total purchase price and just how old and tired they are.

Just keep in mind thst a $7k engine may still be a $25k project.

If the engines are under the back deck, like in many sportfishers, they can be disconnected and plucked right out.

When my boat's PO rebuilt the engines in my boat, he had to remove the entire galley to get them out. When I had to do it again, because of a problem with that work, I had an easier time because the galley layout allowed for better serviceability. But it was still a lot of effort to lift it turn it, move it, lower it, reposition the A-frame, and repeat until it was on the back deck where it could be plucked.

To install an $8500 engine cost me $20k by the time ai had it shipped and installed. And, more than that my the time I had everything squared away after.

I have a friend who's engine replacement has been torturing him for months. It didn't run right at start-up and sellers is hiding.

I have another friend who is having the engine in his sailboat rebuilt now. It was supposed to be done in November. He is now hoping before March. Nothing went wrong. Nothing stopped. Everything has just been moving very slowly.

Replacing an engine isn't something I'd want to do in a boat I hadnt bought yet, unless I really planned to keep it for a long time. From my experience and observation it is a deep hole to dig ones way out of. Not impossibly deep. Not impracticable deep. But big pain deep.

 

[psneeld]

Just keep in mind thst a $7k engine may still be. A $25k project.

If the engines are under the back deck, like in many sportfishers, they can be disconnected and plucked right out.

When my boat's PO rebuilt the engines in my boat, he had to remove the entire galley to get them out. When I had to do it again, because of a problem with that work, I had an easier time because the galley layout allowed for better serviceability. But it was still a lot of effort to lift it turn it, move it, lower it, reposition the A-frame, and repeat until it was on the back deck where it could be plucked.

To install an $8500 engine cost me $20k by the time ai had it shipped and installed. And, more than that my the time I had everything squared away after.

I have a friend who's engine replacement has been torturing him for months ☆ didn't run right at atart-up and sellers is hiding.

I have another friend who is having the engine in his sailboat rebuilt now. It was supposed to be done in November. He is now hoping before March. Nothing went wrong. Nothing stopped. Everything has just been moving very slowly.

Replacing an engine isn't something I'd want to do in a boat I hadn't bought yet, unless I really planned to keep it for a long time. From my experience and observation it is a deep hole to dig ones way out of. Not impossibly deep. Not impracticable deep. But big pain deep.

Thanks...but with my way dealing with the engine sea trial issue...I ALWAYS view replacing an engine at some point... so the boat layout has to make it easy. The trawler we are talking about it would have been easy peezy for me. And depending on how the replacement engine came...may have been just a couple thousand more for yard assistance. But that's me and why I may do things a lot differently than others. It doesn't mean they can't, just gotta know the pieces and parts for every decision.

I've done engine replacements on other boats before and also removed and reinstalled my tranny myself along with the whole drive train. As Shawn pointed out, I also ground the whole bottom off to well below the gel coat and replaced many layers of glass all by myself that several surveyors were impressed with.

I couldn't afford boating if I couldn't do these things and understand why many rely on other professionals to do the heavy lifting. Especially if they have had bad experiences along the way. That's what I couldn't afford paying others till just recently.

 

[ksanders]

Definitely a deal killer for me. There are only two reasons to avoid a 5-min WOT test. Either the seller fears the engine cannot handle it even though it was designed for WOT far in excess of 5-mins. Or they simply don't understand diesels and have superimposed their auto/gas engine "redline" mindset to which I wonder what other carry-over practices they bring to maintenance.

Either way, I want no part of the boat or the seller. I appreciate the heads-up from a reluctant seller. Saves both the buyer and seller (and broker) brain damage.

Peter

I agree 100%

If an engine will not safely put out it's full rated power then something is wrong with it, and as a buyer I have a right to know the engines condition before closing on the boat.

 

[STB]

Thanks...but with my way dealing with the engine sea trial issue...I ALWAYS view replacing an engine at some point... so the boat layout has to make it easy. The trawler we are talking about it would have been easy peezy for me. And depending on how the replacement engine came...may have been just a couple thousand more for yard assistance. But that's me and why I may do things a lot differently than others. It doesn't mean they can't, just gotta know the pieces and parts for every decision.

I've done engine replacements on other boats before and also removed and reinstalled my tranny myself along with the whole drive train. As Shawn pointed out, I also ground the whole bottom off to well below the gel coat and replaced many layers of glass all by myself that several surveyors were impressed with.

I couldn't afford boating if I couldn't do these things and understand why many rely on other professionals to do the heavy lifting. Especially if they have had bad experiences along the way. That's what I couldn't afford paying others till just recently.

In my case, I had plenty of mechanical skill to disconnected and reconnect the engine and do the related mechanical work. That wasn't the issue. The paid mechanics would probably have preferred I was less involved in that!

What I, myself, lacked was the know-how to do the gymnastics to get it out of the boat using the A-frame while minimizing damage to the boat. And even the mid-career professional mechanic needed the help of another mechanic and apprentice from his team to manage the project. Often times one was in the hole, one had the top of the engine, and one was operating the a-frame's come-along or similar. We could probably have reduced thst crew by one person, but not by much more than that.

We could have reduced the shop time if I'd done more myself and we could have used fewer mechanics that way -- butbthen the boat would have been down for weeks, not ~3 days.

Part of my price-paid was to get it done, start-to-finish fast. But, I've found that price is always worth paying -- delay grows, I've found.

 

[C lectric]

I suggest you do what is necessary to control the oil drips from a to high oil level.
I faced that years ago and when I stopped the overfills the engine stopped the leaking AND it stopped alarming. A note tied to the filling port? In my case there were about 2 litres to much. The dipstick was mismarked.

Moisture meters are usefull EXCEPT , and I am serious, shortly after a rain or heavy dew. The FRP will absorb enough moisture, yet not leaking, to cause the meter to reed quite high. The decks need to be allowed time to dry.

I have a meter and I discovered this when I was measuring after a heavy overnight dew even after mopping the deck dry. Before I use the meter I now wipe the area and Let it sit for a couple of hours as the day wore on and the meter dropped big time. THe exterior will absorb some moisture which can seriously affect the readings.
Wipe the deck dry and let it sit. Just allow time for any new dew to dissipate.
I have a boat with lots of varnish and I often started long before the sun was up. Just enough light to see decently.
I would alcohol wipe any surfaces to remove the dew I intended to lay a coat of varnish on,
The dew moisture will reform , often within minutes. I carry an alcohol soaked rag, with me, not dripping, and wipe again just before I lay the first varnish coat down. Next day the same procedure.

But meters can be fooled with simple surface moisture from dew.

So take notice about what you are doing.

And surveyors opinions are opinions. Try to do something about the points he mentioned. It may not take much to put it over the top.

 

[mvweebles]

....I ALWAYS view replacing an engine at some point... so the boat layout has to make it easy. The trawler we are talking about it would have been easy peezy for me. And depending on how the replacement engine came...may have been just a couple thousand more for yard assistance.

If it's so easy to replace an engine, than why so hesitant to do a WOT test? You would be in a great position to accurately evaluate the risk and mitigate the consequences if needed. Even more reason to have no objection to a WOT test.

I know many of the boats on TF have old engines. But that's no reason to give the engine a pass. My 1970 Willard with Perkins 4.236 runs like a sewing machine. I wish everything on my boat was as reliable as the engine has been. I would not have left the US had I thought I needed to baby the engine.

Sellers can certainly set whatever terms they want. But they should not be surprised if they scare off knowledgeable buyers. The seller's intentions may be pure, but a buyer who is deprived of important due diligence has reason to view the seller as acting in bad faith.

Peter

 

[psneeld]

If it's so easy to replace an engine, than why so hesitant to do a WOT test? You would be in a great position to accurately evaluate the risk and mitigate the consequences if needed. Even more reason to have no objection to a WOT test.

I know many of the boats on TF have old engines. But that's no reason to give the engine a pass. My 1970 Willard with Perkins 4.236 runs like a sewing machine. I wish everything on my boat was as reliable as the engine has been. I would not have left the US had I thought I needed to baby the engine.

Sellers can certainly set whatever terms they want. But they should not be surprised if they scare off knowledgeable buyers. The seller's intentions may be pure, but a buyer who is deprived of important due diligence has reason to view the seller as acting in bad faith.


Peter

I have my reasons and you have yours...I can see this never ending with never agreeing.

While I understand your point, for people wanting to use their boat while waiting to sell, I chose not to make ANY more work for me than I have to.

I sold my boat with the full understanding that I priced it if someone wanted to drop a new engine in, it was priced more than right and I told them that and don't dare waste my time.

Not sure if anyone who has ever dealt with me ever accused me of acting in bad faith. All buyers who bought my boats have stayed in touch for years.

If you don't understand that, OK....didn't you have your boat in a yard for awhile while it was brought up to what you wanted?

I never had that luxury with any of my boats...buy, move aboard, refurbish as I use them and get on with life. 2 different styles, neither right or wrong.

 

[mvweebles]

I have my reasons and you have yours...I can see this never ending with never agreeing.

While I understand your point, for people wanting to use their boat while waiting to sell, I chose not to make ANY more work for me than I have to.

I sold my boat with the full understanding that I priced it if someone wanted to drop a new engine in, it was priced more than right and I told them that and don't dare waste my time.

If you don't understand that, OK....didn't you have your boat in ta yard for awhile while it was brought up to what you wanted?

I never had that luxury with any of my boats...buy, move aboard, refurbish as i use them and get on with life. 2 different styles, neither right or wrong.

I actually think we agree somewhat. You priced your boat accordingly, sounds like it was a fair price. Boomerang/Shawn has also priced the boat exceedingly fair. Seriously, $50k for a decent boat that has a known provenance of responsponsible ownership?

As a buyer, I'd want to know what I was getting into. Even if the boat is priced as if the engine is unknown and perhaps sketchy with zero credit forthcoming if it fails a WOT test (for example), I'd want to understand what I'm dealing with.

When I was assisting buyers, I would ask the seller to provide someone to operate the boat. If at any point they became uncomfortable with the WOT test, they could terminate it; long before any damage occured. Sure, if the boat was oil-starved it could throw a rod or something, but that should never happen unless there is some serious neglect - all within the seller's control.

I didn't do a ton of sea trials, but I remember one failed due to WOT test. Turns out the boat was marginally powered (Bayliner 3288 with Hino's - gas was a better option for this boat); and it would not get on-plane unless the bottom was clean, and even then she had to run light so was essentially a displacement-speed boat. Buyer really, really wanted diesels so he bought the boat anyway.

Peter

 

[Delta Riverat]

On our sea trial the broker insisted I peg the throttles and make repeated hard port and starboard turns. Yeah, big doughnuts in the water with lot's of wake and froth and busting through these wakes!

Another reason I like this broker -

 

[boomerang]

For the record and just so everyone is clear, as I posted earlier, I did run the engine WOT (a minute or less?) to check the RPM's ,temps etc. I just didn't run the boat at WOT for an extended period time, as I explained to the prospect and the surveyor before we left. I'M just not comfortable doing it and never have been. If others are ok with it ,thats good; it's their boat! There's no concrete right or wrong.

 

[jleonard]

I’m comfortable with a WOT test. What I’m less comfortable with is the “high idle” test, which is in neutral and putting the fuel lever to max, especially if its done with the linkage disconnected with your face down next to the engine.
That freaks me out somewhat. If a belt breaks loose or something grenades it could be scary.
But thats done all the time also, especially if WOT cant be met.
The brand new Cummins 6bta that I repowered my old Mainship with had maybe 5 minutes of run time on it….just enough to get the air out of the cooling system, when the Cummins tech checked high idle. That made me cringe for sure!!

 

[rslifkin]

For the record and just so everyone is clear, as I posted earlier, I did run the engine WOT (a minute or less?) to check the RPM's ,temps etc. I just didn't run the boat at WOT for an extended period time, as I explained to the prospect and the surveyor before we left. I'M just not comfortable doing it and never have been. If others are ok with it ,thats good; it's their boat! There's no concrete right or wrong.

That sounds like an adequate test to me, considering a Lehman isn't expected to run WOT for long periods anyway.

I’m comfortable with a WOT test. What I’m less comfortable with is the “high idle” test, which is in neutral and putting the fuel lever to max, especially if its done with the linkage disconnected with your face down next to the engine.
That freaks me out somewhat. If a belt breaks loose or something grenades it could be scary.
But thats done all the time also, especially if WOT cant be met.
The brand new Cummins 6bta that I repowered my old Mainship with had maybe 5 minutes of run time on it….just enough to get the air out of the cooling system, when the Cummins tech checked high idle. That made me cringe for sure!!

As terrible as that test seems, it does make sense to make sure the governor is set properly and not restricting the engine from reaching its proper full RPM. Only valid with mech injection diesels though, no point in doing it with an electronic system.

 

[PierreR]

For me a lot depends on the boat and the engine for WOT test. I am with Peter but limiting some applications to a couple of minutes is okay for me.

You take something like full blown CAT 3116's in a heavy boat with cramped engine room and I will agree to limit the WOT test. At the other end of the spectrum is a Gardner 6L3 in a deep full displacement boat driving a CCP that better run all day at WOT (900rpm)and purr.
I wanted a 5 minute WOT test on my present boat, a heavy boat with small NA Detroit's. If it would not do five minutes, I was not interested. The broker was hesitant and I agreed to cut it short if the temps climbed, excessive vibration or excessive smoke. I had the engine room covers off. The boat passed with flying colors.
So how have I treated the boat since. WOT for 13 minutes to catch a lock I would wait two hours for. Naturally Aspirated Detroit's just don't want to be babied all the time.

 

[jleonard]

What does a cramped engine room have to do with it?
If its heat your concerned with then all the more reason to do a WOT test and measure ambient temp in the engine space.

 

[psneeld]

Just as not doing the WOT test is a reason to pass on a boat, why would failing the test for anything but a piston through the block be a reason also?

If the fix is so simple to not risking the test and having to fix something, the same could be said for not passing on a failure either.

Maybe why seeing the issue either way is not unreasonable.

 

[mvweebles]

As Sunchaser noted early in this thread-diversion, WOT gives more information than whether the engine blows up or not. Whether it's propped correctly, shaft vibration, engine mounts, overheating, etc.

Unlike gasoline engines common diesels in TF boats are designed to run at WOT. Period. Some are designed to do so continuously, some have an intermittent duty cycle. But they are designed to run WOT. Inability of the engine to do so is a defect just as any other survey defect is.

The concern of people who don't want their engines run at WOT is founded in lack of knowledge about diesel engines and reliance of gasoline engines with redline RPM as an example. WOT will not cause a reasonably healthy diesel to throw a rod. It will display other indicators such as heating-up or black smoke long before any damage is caused which will terminate the test.

That said, certainly up to the seller whether they are comfortable with any test. Heck, nothing says they need to allow the boat to be hauled for a survey or any other due diligence item. Just don't get offended when the buyer either walks away or pitches an offer based on lack of due diligence.

Peter

 

[PierreR]

What does a cramped engine room have to do with it?
If its heat your concerned with then all the more reason to do a WOT test and measure ambient temp in the engine space.

Heat is the concern and I would not run 3116's at high rpm for long. I would want to know the engine can do it for a couple minutes.
The thing is, I am going to low ball a boat with 3116's in it to begin with so why do a stringent test. They serve their purpose. A lot of power from a small light package at a price. All boats are a compromise.

 

[psneeld]

As Sunchaser noted early in this thread-diversion, WOT gives more information than whether the engine blows up or not. Whether it's propped correctly, shaft vibration, engine mounts, overheating, etc.

Unlike gasoline engines common diesels in TF boats are designed to run at WOT. Period. Some are designed to do so continuously, some have an intermittent duty cycle. But they are designed to run WOT. Inability of the engine to do so is a defect just as any other survey defect is.

The concern of people who don't want their engines run at WOT is founded in lack of knowledge about diesel engines and reliance of gasoline engines with redline RPM as an example. WOT will not cause a reasonably healthy diesel to throw a rod. It will display other indicators such as heating-up or black smoke long before any damage is caused which will terminate the test.

That said, certainly up to the seller whether they are comfortable with any test. Heck, nothing says they need to allow the boat to be hauled for a survey or any other due diligence item. Just don't get offended when the buyer either walks away or pitches an offer based on lack of due diligence.

Peter

I do know something about diesel engines and I still think the way I do. I have run hundreds of diesel boats in the last 23 years... recreationally and commercially under all kinds of situations.

You completely missed the point of my last post as your post #42, first paragraph made my point.

 

[mvweebles]

Not sure what your point is Psneeld. Best I can figure is you assume an engine needs to be replaced, which is "easy peasy" so no need to test it. Whatever works for you, but many buyers are not as eager to buy a boat that may need major repairs. Let's face it, using your logic, might as well assume the entire boat is a PoS and not even bother surveying it in the first place.

For buyers (and vis a vis sellers) who are interested in due diligence on a boat prior to purchase, Steve D'Antonio provides several articles on engine survey and diagnostics, including why a WOT makes sense.

https://stevedmarineconsulting.com/the-art-of-the-engine-survey/

All I can say is that, as a buyer, I consider it a very bad sign if a seller is unwilling to allow due diligence on a major purchase.

To be clear, the seller of this boat - Boomerang - said he's fine with reasonable testing including WOT done with caution (which is always the case - test should be halted id any signs of problems arise). This really looks like a fairly priced example of a 40 foot Taiwan trawler. Surprised it's still available.

Peter

 

[psneeld]

Not sure what your point is Psneeld. Best I can figure is you assume an engine needs to be replaced, which is "easy peasy" so no need to test it. Whatever works for you, but many buyers are not as eager to buy a boat that may need major repairs. Let's face it, using your logic, might as well assume the entire boat is a PoS and not even bother surveying it in the first place.

For buyers (and via a vis sellers) who are interested in due diligence on a boat prior to purchase, Steve D'Antonio provides several articles on engine survey and diagnostics, including why a WOT makes sense.

https://stevedmarineconsulting.com/the-art-of-the-engine-survey/

All I can say is that, as a buyer, I consider it a very bad sign if a seller is unwilling to allow due diligence on a major purchase.

Peter

In THIS case based on the original post...my advice or how I do things with $50,000 or less boats as I POSTED BEFORE is , or at least might be different if I was buying a MUCH more expensive boat with MUCH more expensive engines. But that ISN'T the case in this thread.

So I stand by my thoughts and respect yours but have a different point of view.

You can continue on to your hearts delight but in the "poor" boat world I have always found the rules and discussions to be on 2 different levels than much of the discussions on TF.

Ever see how many boats out there running around that used to be nice, inboard boats but now have an outboard hanging off the stern? That's the last step in life of many of these older boats before they become green blobs in some boatyard.

Teach the gang all you want, I have finished saying my bit.

 

[rslifkin]

Any engine, even a gas engine is meant to be able to run at WOT at least briefly. But different engines will have different lengths of time that are appropriate to run at WOT and different concerns with longer periods of running at WOT. So the maximum appropriate length of a WOT test will vary.

Personally, I wouldn't run WOT for long on any engine rated as "high output" or with a "pleasure craft" rating (unless the manufacturer specifies a length of time at WOT that is safe), especially if the engine doesn't reach rated RPM. For heavier duty ratings, a few minutes should be no big deal, with the extreme end being something like a Gardner or continuous rated big Cat, M1 rated JD, etc. that should be able to run at WOT indefinitely.

Even with my gassers, I generally open the boat up at some point early in the season to make sure we reach expected speed and RPM. I just don't hold it there once the boat is done accelerating, but acceleration to a steady top speed isn't instant after pushing the throttles up from max continuous to WOT. It's a good 30 seconds I think. Doing that won't hurt the engines, they would just wear quickly if run like that all the time (and in particular burning up exhaust valves can be a concern).

A boat that doesn't make expected speed / RPM on a WOT test isn't automatically a major problem, but it indicates that there's something that should be investigated in the drivetrain, anywhere from the engine to the prop. And the price should reflect that a prop change or some repairs may be needed.

No WOT test would need to be priced as if the engine is likely to need significant work or is tired and near end of life. If the price reflects that, fine, but if I could find a similar boat in similar condition where engine health could be more accurately assessed then...

 

[TBill36]

I would think that running WOT, either loaded or unloaded, for somewhat short periods of time should not be a concern. Most construction equipment is run at elevated rpms and then loaded depending on the task. Think about how an excavator or front end loader is operated. They don't elevate rpm as the load is applied. They start out with the rpm elevated and then apply the load.

Yes, boat loading is different, but the basic engine is the same and I would think WOT should not be a concern for short durations.

 

[SteveK]

I do know something about diesel engines and I still think the way I do. I have run hundreds of diesel boats in the last 23 years... recreationally and commercially under all kinds of situations.

You completely missed the point of my last post as your post #42, first paragraph made my point.

Seems like an exaggeration, but I suppose I suppose that is possible.

 

[STB]

This is one of those situations where a bit of understanding in both directions us useful, I think.

Sellers really should let buyers test the boat in this respect until there a limit is reached. Obviously if something bad is happening (temp rise, black smoke, etc), the limit has been reached and there is no reason to go further or continue. But, until getting there, why stop the buyer? It can only lose the buyer.

Similarly, buyers can also be thoughtful. If the seller lets them run it up to 90% for an ended period of time and all is well. What is the extra 10% likely to show of concern? Why lose the boat over a seller's superstition? Boaters are full of superstitions.

Sure. Sellers can say no to the test, but why?
Sure. Buyers can walk over the difference between 90% and 100%, but why?

If a seller won't let a buyer get up to a high cruise speed and stay there a while, that's a totally different story.