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My engine has a OEM spec for max RPM... something I never used as something like 2100rpm give me hull speed.. Conditions matter.... and it makes sense that hull speed rpm is not to "red line"
So... what is learned by running engine at full rpm...is that in gear or neutral?
Only use I can see in gear would be in a "panic situation" to avoid a way too close hazard.
 

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Yes, I would be present for a sea trial. For one thing, I can operate my boat more smoothly than any stanger, since I know her systems better. I will make her look better. If you don't want to be involved in a negotiation, don't talk.

And yes, if you refused to let me sail the boat hard, you just told me what I need to know. I'm walking. While I should not be allowed to do anything dangerous during a seatrial, full RPMs and sailing with the rail in the water are normal for a test, and if you think your boat is too fragile for that, then tell me that up front. Otherwise, I'll assume you are a liar.

30 knots is a bit much, but my last sea trail was in 20-25 and reefed. I bought the boat. Certainly anything up to 1 reef is reasonable, unless you believe the boat can't handle that....:sneaky:
 

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Yes, I would be present for a sea trial. For one thing, I can operate my boat more smoothly than any stanger, since I know her systems better. I will make her look better. If you don't want to be involved in a negotiation, don't talk.

And yes, if you refused to let me sail the boat hard, you just told me what I need to know. I'm walking. While I should not be allowed to do anything dangerous during a seatrial, full RPMs and sailing with the rail in the water are normal for a test, and if you think your boat is too fragile for that, then tell me that up front. Otherwise, I'll assume you are a liar.

30 knots is a bit much, but my last sea trail was in 20-25 and reefed. I bought the boat. Certainly anything up to 1 reef is reasonable, unless you believe the boat can't handle that....:sneaky:
I suspect most sea trials are conducted in benign conditions... not challenging ones.

What do you want to learn in a sea trial? Be specific
 

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30 knots is a bit much, but my last sea trail was in 20-25 and reefed. I bought the boat. Certainly anything up to 1 reef is reasonable, unless you believe the boat can't handle that....:sneaky:
Did you put the rail in the water? :p

Since one does not normally pick the weather on the day of the sea trial, and the boat may be located an impractical distance from open sailing waters, one cannot expect to sail the boat hard on a sea trial.

For example, the last boat we sold was surveyed 16nm up a river with a large tidal flow (closest marina within 100nm that could haul the boat). It is unreasonable to expect to travel 3hrs to open water, sail around, then 3hrs back to the yard. Besides, there was no wind the day of the survey if we did travel to open water. We went out on the river for an hour, did the engine tests, raised all the sails, worked the winches, etc.

Absent a one-off design, one should already have an understanding of how the boat sails before making an offer. The sea trial is to show that the systems work and are sound.

It is more difficult for a surveyor to assess sea trial points while sailing and motoring into 25kt winds and accompanying seas than in calmer conditions.

Mark
 

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I suspect most sea trials are conducted in benign conditions... not challenging ones.

What do you want to learn in a sea trial? Be specific
Be specific? You know, of course, that the list would be long.

  • Will the engine run WOT for at least 15 minutes without overheating? The OP thought this was unfair, but I think this is a TOTALLY FAIR test. I can't imagine not running the engine at WOT for a time. That's why you are there.
  • What is the sail shape under a real wind load? Do they point and how is the helm? You can't judge the drive and helm in light conditions. Polyester sails often look good until the wind blows.
  • Does the furler work smoothly in the wind (no, this is not the same as in light conditions)? They can be fine at the dock, but friction from failed bushings and bearings is only revealed under some load. Furling in 10 knots up wind (instead of off the wind like a seaman) is enough.
Then, there are boat-specific details that in theory you could already know, but not all boats are common with reliable reviews:
  • Does she pound? Specific to cats, does the bridge deck pound going to weather?
  • How does she motor into the wind? Many outboad-driven boats will cavitate, others will not.
  • How is the motion? The numbers don't tell you everything.
  • How does she tack (this is an issue with many cats, but all boats to some extent)?
  • Is she dry or wet?
A sea trial in zero-to-nothing is very nearly a waste of time. I would reschedule, and have.

No, I'm not suggesting a near gale, but 10-15 knots is a good window. But you don't really get to pick and choose, since these things are scheduled. Might be a little more, and that's when you see how good she is. What I am saying that is some buyers will walk if you require she be babied during trials. We'll smell a rat and run.
 

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You shouldn’t have to actually sail, a surveyor should be able to tell by inspection if the boat is sound. If you need to sail with a rail in the water it sounds like you’re not familiar with the boat and want to test its capabilities, that’s not what a sea trial is for, when you decide you want to buy the boat is when you should know what is capable of.
 

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Did you put the rail in the water? :p

I did get a hull nearly out of the water (cruising cat), so yes, the multihull equivalent.

Since one does not normally pick the weather on the day of the sea trial, and the boat may be located an impractical distance from open sailing waters, one cannot expect to sail the boat hard on a sea trial.

Oh yes I can expect a good trail in open water. Motoring around a harbor is a waste of time.


For example, the last boat we sold was surveyed 16nm up a river with a large tidal flow (closest marina within 100nm that could haul the boat). Yup, that is different. It is unreasonable to expect to travel 3hrs to open water, sail around, then 3hrs back to the yard. Besides, there was no wind the day of the survey (Yes, that is the luck of the draw. I might accept that or I might reschedule. 10-day forecasts are pretty good.) if we did travel to open water. We went out on the river for an hour, did the engine tests, raised all the sails, worked the winches, etc.

Absent a one-off design, one should already have an understanding of how the boat sails before making an offer. The sea trial is to show that the systems work and are sound. (Obviously. But the OP implied "no WOT." That is a reasonable test. Regarding multihulls, many are not common.)

It is more difficult for a surveyor to assess sea trial points while sailing and motoring into 25kt winds and accompanying seas than in calmer conditions. Sorry? But as you pointed out, there will usually be flat water in the harbor and approaches, so generally a minor issue. But I understand and accept your point for some locations.

IME, it is usually a seller that has a boat that either he knows or may have faults that will be by rigorous testing.


Mark
 

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Be specific? You know, of course, that the list would be long.

  • Will the engine run WOT for at least 15 minutes without overheating? The OP thought this was unfair, but I think this is a TOTALLY FAIR test. I can't imagine not running the engine at WOT for a time. That's why you are there.
Is WOT wide open throttle? My engine temp will rise... I suspect the cooling system can't "keep up" with the additional heat generated. Who runs their engine for 15 minutes WOT? I never have in 36 years.
  • What is the sail shape under a real wind load? Do they point and how is the helm? You can't judge the drive and helm in light conditions. Polyester sails often look good until the wind blows.
  • Does the furler work smoothly in the wind (no, this is not the same as in light conditions)? They can be fine at the dock, but friction from failed bushings and bearings is only revealed under some load. Furling in 10 knots up wind (instead of off the wind like a seaman) is enough.
I think some can assess a furling system is typical conditions. I don't know how you use yours, but I have a Profurl, which I can and DO winch in. and furl in at almost any wind speed.

Then, there are boat-specific details that in theory you could already know, but not all boats are common with reliable reviews:
  • Does she pound? Specific to cats, does the bridge deck pound going to weather?
  • How does she motor into the wind? Many outboad-driven boats will cavitate, others will not.
  • How is the motion? The numbers don't tell you everything.
  • How does she tack (this is an issue with many cats, but all boats to some extent)?
  • Is she dry or wet?
These are somewhat subjective and dependent on conditions...
Motion is subjective... related to LWL, hull form, wind and sea conditions
Relative.. may be important to a racer... critically so.
Relative... my boat is quite dry to sail,. but there is sea spray.. most conditions the boat is dry

But you are not going to learn all these in a one hour sea trial PERIOD. Better yet is to research the boat and ask the owner... assuming you can trust their responses. But is trust important when doing such a transaction?


A sea trial in zero-to-nothing is very nearly a waste of time. I would reschedule, and have.

You can see how boat motors, steers.

No, I'm not suggesting a near gale, but 10-15 knots is a good window. But you don't really get to pick and choose, since these things are scheduled. Might be a little more, and that's when you see how good she is. What I am saying that is some buyers will walk if you require she be babied during trials. We'll smell a rat and run.
10-15 true is ideal...
8-10 is good enough for most "tests"
 

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A sea trial in zero-to-nothing is very nearly a waste of time. I would reschedule, and have.

No, I'm not suggesting a near gale, but 10-15 knots is a good window. But you don't really get to pick and choose, since these things are scheduled. Might be a little more, and that's when you see how good she is. What I am saying that is some buyers will walk if you require she be babied during trials. We'll smell a rat and run.
Reschedule with a surveyor? As a buyer, I'd probably bulk at a sea trial with a surveyor, and another just for the seller to see if he likes sailing the boat.

Yes, I agree that 10-15kt is a good window, and doubt anyone would have a problem with that.

Would also run if the sellers refused to have the systems tested, like WOT for a practical time. As for sails, unless unusual claims are made, these are sold as is. A seller could say the dacron stretches too much, while the buyer says it does not. Without a sail survey by a professional, this is a tricky negotiation.

Motion, tacking, pounding, dry/wet, etc - one should understand this before making an offer. These are also highly subjective aspects. If I was the seller, and the buyer wanted to use a sea trial to determine these factors, I'd agree only if the buyer agreed to forfeit the escrow if they didn't meet expectations. It would tell me that the buyer did not do their homework. Otherwise I would let the sale fall through rather than keeping it off the market or letting the perception get out that the boat was failing sea trials.

Mark
 

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what is learned by running engine at full rpm.
Will it make max rated RPM, for starters. Not all boats will, which can be a symptom of the wrong prop pitch or an engine problem. Could, be an issue with the tach or it’s wiring too, so confirming RPM with a laser tach is the best method. Does she overheat too.

sailing with the rail in the water
I see you clarified this in a subsequent post. It’s the buyer’s right to say they’ll need this, but I’d be happy kicking that buyer to the curb. It’s unnecessary, IMO, to determine system functionality. The sea trail is not a joy ride and I would not be convinced the buyer wasn’t just playing. They can play all they want, after the check clears.
 

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I am responding, not as a buyer but as a seller of my boat.
As such... I still have the original prop.. so hard to conceive if is not proper design... boat motors at hull speed... and it doesn't need full "WOT" to achieve that.
So I don't know engines and would think no one pushes a motor passed the red line to WOT and I can't imagine the cooling system is designed for those operating temps. I do not that when I pushed the throttle past the normal needed for hull speed temps do creep up a bit. If the gauge stays in the red zone... it is a concern and means blocked/fouled hose or messed up impeller or busted exhaust elbo, I have pushed the throttle all the way for a very brief burst.. so I know it can get there... but don't know what this demonstrates about the motor.

It is EXTREMELY rare to get the rail in the water on my boat.... probably because the high freeboard, In fact it's not even likely to have the ports inside the water... Sure they get splashed. THAT heeled is bad sailing (on my boat)... I sail at 15° and 20° is too much... boat is making too much leeway.
 

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Governed WOT is "red line" on a diesel. The cooling systems (and rest of engine) are designed to operate within normal coolant temp range at WOT under load for a set amount of time. This time is usually in the operating manual, but is a reasonable amount of time - 20min to 2hrs depending on recreational engine model. If it is a commercial engine, then it can run there continuously. The temp will creep up under WOT, but should remain within operating specs.

For example, most gensets are operating at governed WOT, and many of these are operating 24/7.

Mark
 

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I still have the original prop.. so hard to conceive if is not proper design.
Sure, but the survey is designed to confirm it, not take your word for it.

no one pushes a motor passed the red line to WOT and I can't imagine the cooling system is designed for those operating temps.
Which red line are you talking about, rpm, temp, pressure? In any event, the engine should operate within them all at WOT, which is the point of testing it. Not sure why that doesn’t make sense.

don't know what this demonstrates about the motor.
It’s but one indicator of the health of the motor and drive train. Simple. Just because you can make hull speed does not mean the engine, transmission and gear are necessarily fine. If any of these had too much back pressure, there may still be sufficient excess HP to get to hull speed, but it would be taking a slow toll on the entire system.
 

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Sure, but the survey is designed to confirm it, not take your word for it.



Which red line are you talking about, rpm, temp, pressure? In any event, the engine should operate within them all at WOT, which is the point of testing it. Not sure why that doesn’t make sense.



It’s but one indicator of the health of the motor and drive train. Simple. Just because you can make hull speed does not mean the engine, transmission and gear are necessarily fine. If any of these had too much back pressure, there may still be sufficient excess HP to get to hull speed, but it would be taking a slow toll on the entire system.
I know I can get the rpms to what I recall is in the Owner's manual and more than I use to cruise. I also know a fouled prop and a bottom add load to the engine.

I don't understand engines and would like to know what a WOT would show? I googled WOT and it's about matching a prop to the engine.

"“An engine that does not reach the rated RPM at wide-open-throttle is an “over-propped” condition, resulting in “lugging.” This high-torque operation puts a tremendous load on the pistons, crankshaft, and bearings. The engine runs much hotter and may overheat from having over-advanced spark timing for the reduced amount of fuel entering the engine. The mechanical strain on an over-propped marine engine is like starting an automobile in third gear from a dead stop at the bottom of a hill. This severe strain can lead to detonation, piston seizure, and engine damage.

On the other hand, an engine that revs past the recommended RPM will have higher than normal wear and can also be damaged by fatigued parts breaking and passing through the engine.

This is why it is so critical to be sure your engine is propped correctly for your boat/engine combination and the type of boating you want to do.”

I would like to add that what your engine does at WOT tells us what it will do at other throttle locations. In other words, if you are lugging at the top end, you will be lugging in the middle and at the low end."
 

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I always want to see the engine run at full rated speed for at least 10 minutes during a sea trial for a boat that I may buy. I spell that out right in the contract. On the other hand, I think that it is irresponsible to put full canvass up in heavy winds on most boats. If that sort of thing is being discussed, I would 100% want to be there for the sea trial & I would expect to veto some requests, even if it caused the potential buyer to walk. Wrecking the boat is not in the seller's best interest.

If I was the seller & I was not going to be there, I would certainly want to know the credentials & experience of the the other guys that are going to be taking the boat out for a spin. One question I would start with would be - Who aboard will be a licensed caption with sailing endorsement? Another would be - Who is going to be responsible for repairs if the boat is run aground, damaged, etc.

A sea trial needs to prove that the boat is seaworthy. It should not be a demolition derby. The responsible party needs to be defined before the boat leaves the dock.
 

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Discussion Starter · #57 ·
Again, thanks for the interest and all input to this thread. I have no issues with driving my boat hard, and I know how it behaves under heavy conditions. My 1990 Clearwater 35' , with a swing keel and rudder, is one of only 7 made, they were built sturdy in Bristol, RI; one of the 7 has circumnavigated. So it is nearly a one off and I feel I would need to spend some time with a substitute captain to get him up to speed. My approach would be to test my boat now, before I have a customer, thru the possible high power conditions to uncover any issues. Nominally, she runs great as I replaced the mixing elbow and had a new serpentine belt system installed recently, so the only issues might relate to the, recently rebuilt, MaxProp settings.

That being said, I do understand that I am very attached to this boat, as only its second owner, and (from this discussion) I have learned that I need to prepare myself to be able to remain apart from any discussion that takes place during the sea trial. Yet, I do want to present the boat in its best light without imposing my self on the potential buyer.

I am early in sale process, so I have time to work on my subtle communication skills.

thanks,
Ron
 

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You shouldn’t have to actually sail, a surveyor should be able to tell by inspection if the boat is sound. If you need to sail with a rail in the water it sounds like you’re not familiar with the boat and want to test its capabilities, that’s not what a sea trial is for, when you decide you want to buy the boat is when you should know what is capable of.
I'm never surprised in the hundreds of sea trials i've done with what fails under moderate stress that should be within the capabilities of the vessel. I've seen shaft flanges disintegrate with a short burst of full throttle (that one I warned them about). I've seen motor mounts that looked fine at the dock but showed broken bolts when the engine moved 1" off the beds under heavy loads in reverse. I've seen exhaust manifolds leaking profusely at high RPM under load which showed no leaks at hull speed RPM. I've seen rudder stock knees move 1/2" with a hard turn of the rudder. I've seen autopilots that had conniptions if you used the jog at hull speed.

If the owner will not permit a little stress what is he afraid of ?
 

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I'm never surprised in the hundreds of sea trials i've done with what fails under moderate stress that should be within the capabilities of the vessel. I've seen shaft flanges disintegrate with a short burst of full throttle (that one I warned them about). I've seen motor mounts that looked fine at the dock but showed broken bolts when the engine moved 1" off the beds under heavy loads in reverse. I've seen exhaust manifolds leaking profusely at high RPM under load which showed no leaks at hull speed RPM. I've seen rudder stock knees move 1/2" with a hard turn of the rudder. I've seen autopilots that had conniptions if you used the jog at hull speed.

If the owner will not permit a little stress what is he afraid of ?
I was unaware of the WOT "test". It hardly seems like a "little stress".... but I don't know much about engines. I do know that my MD17D which is quite old has a recommended OEM "RPM operating range.". As I noted in an earlier post that I never have had a need to even run at the high end of this range because I can achieve hull speed as lower RPMs.
Perhaps there are times when a burst of full throttle may be called for. I'd like to hear of some examples. But surely not for 15 minutes WOT.
My naive sense of this matter.... is that if the mfg gives a recommend max operating RPM, the user should observe it.

WOT seems to be excessive stress. Who knows, it may cause some damage.
 

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Feels like the argument is going in circles. The fact that you don't need to normally run at WOT has absolutely nothing to do with why one is testing the health of the engine by doing so. It's been explained several times above, you even quoted something from the internet that explained.

Get the manual for your engine and check for an operating limitation at WOT, after break-in. I bet you don't find one, you're just using your imagination.
 
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