Sea Trial

[Dreamboat]

Has anybody ever heard of a surveyor asking to run the boat at WOT for half an hour during a sea trial?

 

[madhatter1]

No, just a few minutes to check RPM and temps. I would never run wide open for 30 minutes.

 

[rsmith]

Back in the day everyone ran Detroits on the pins. I’ve had mine on the pins for 3-4 hours coming home from the canyons to make a tournament weigh in. IMHO this hull speed crap causes more engine damage than running them hard and keeping them clean of soot. In reality the Detroit ops manual calls for advancing the throttles to full rpm then reducing 200 rpm for cruise. In reality what’s another 200 rpm on a heavy overbuilt Diesel engine?

 

[Scarlett]

As a surveyor I have had clients insist on running WOT for. Long period and have had them actually get in fights with owners who did not want to. Had one Hino diesel overheat after about 20 min on the pins and blew 2 hoses on a pair of Cummins. Most mechanics I work with only want to see WOT for about 5 minutes

 

[Pascal]

I ve never seen it done for that long either. 2 to 3 minutes to verify RPM and temps.

Last survey i was involved with was the sale of the 84 Lazzara I ran for a few years. After all the usual the surveyor asked me to come to idle and then apply full power (1650hp C32s) to accelerate the boat again to WOT. I refused. I turned to the buyer and explain to him he didn’t want me to put that much stress on the drivetrain. He agreed. I did it by gradually going to WOT over a period of about 5 seconds. Surveyor wasn’t happy but the buyer was

 

[cww]

I ve never seen it done for that long either. 2 to 3 minutes to verify RPM and temps.

Last survey i was involved with was the sale of the 84 Lazzara I ran for a few years. After all the usual the surveyor asked me to come to idle and then apply full power (1650hp C32s) to accelerate the boat again to WOT. I refused. I turned to the buyer and explain to him he didn’t want me to put that much stress on the drivetrain. He agreed. I did it by gradually going to WOT over a period of about 5 seconds. Surveyor wasn’t happy but the buyer was

That's nuts was the surveyor going to open his own wallet up if it broke a shaft?

 

[SEVEN]

All of my purchases have been 5 min at 1500, 5 min at 2000 and 5 min at WOT.

 

[Avenger]

RTFM

As usual, there is a difference between commercial and pleasurecraft ratings, and the manufacturer will specify how many minutes out of an hour are permissible within the context of that rating.

Do that. I don't understand the fear people have of WOT. The engine is made to do it, and if everyone is afraid of it when you're buying the boat something is wrong. And if you break a shaft going to WOT something is seriously wrong.

Why wouldn't you want to test the performance limits of a boat you are paying a lot of money for?

Some people seem to think these things are made of Corinthian leather instead of iron and steel.

 

[jap201]

agree 100%. the only change I'd make to your comment is switch "Corinthian leather" with "fine china".

RTFM

As usual, there is a difference between commercial and pleasurecraft ratings, and the manufacturer will specify how many minutes out of an hour are permissible within the context of that rating.

Do that. I don't understand the fear people have of WOT. The engine is made to do it, and if everyone is afraid of it when you're buying the boat something is wrong. And if you break a shaft going to WOT something is seriously wrong.

Why wouldn't you want to test the performance limits of a boat you are paying a lot of money for?

Some people seem to think these things are made of Corinthian leather instead of iron and steel.

 

[SKYCHENEY]

We ran DD's for years in trucks and heavy equipment. Our main mechanic wanted to see them run at full throttle and this is guy who had to rebuild them. I wouldn't be afraid to run them up. If your cooling system is functioning properly, there is no issue.

 

[Avenger]

agree 100%. the only change I'd make to your comment is switch "Corinthian leather" with "fine china".

I was going to go with something less language appropriate,... but I settled on Ricardo Montalbán and "Rich Corinthian Leather." Which outstrips "Rich Crushed Velour."

Perhaps the Chrysler connection was too delicate.

 

[Pascal]

We ran DD's for years in trucks and heavy equipment. Our main mechanic wanted to see them run at full throttle and this is guy who had to rebuild them. I wouldn't be afraid to run them up. If your cooling system is functioning properly, there is no issue.

Did you mechanic suggested reving up the engine and dumping the clutch? That’s the road equivalent to going to WOT without letting the 100k+ boat accelerate.

 

[cww]

RTFM

As usual, there is a difference between commercial and pleasurecraft ratings, and the manufacturer will specify how many minutes out of an hour are permissible within the context of that rating.

Do that. I don't understand the fear people have of WOT. The engine is made to do it, and if everyone is afraid of it when you're buying the boat something is wrong. And if you break a shaft going to WOT something is seriously wrong.

Why wouldn't you want to test the performance limits of a boat you are paying a lot of money for?

Some people seem to think these things are made of Corinthian leather instead of iron and steel.

Is it actually okay to just throw it up to WOT instantly instead of walking the sticks up at a measured pace? I don't know one way or the other, aside from that I got yelled at for doing that once as a kid when driving my dad's boat. The explanation was that there's a lot more force involved going to full throttle instantly than increasing the throttles at a measured pace and it could break the shaft or couplings. The ti's in my boat put out something like 1500lb/ft+ of torque at 1500rpm, I'm sure bigger engines like the 12's in rsmith's boat or C32's in Pascal's are even higher. Isn't that a lot to put into the shafts and props all at one time?

 

[Avenger]

Nobody is suggesting a neutral drop.

But if going from forward idle to WOT is going to break the boat, I wouldn't buy that boat.

 

[Avenger]

Seriously, don't you think the engineers that spec'd the shafts understood the torque loads that the engines could produce?

If they didn't, you don't want that boat.

 

[Pascal]

Yes pretty much every boat or repower is designed so the shafts can take the load from the engines in normal conditions. I know that when I repowered my 53, the prop shop and the cummins dealer ran the calculations. To ensure the safety factor was adequate

But the question remains why would you want to throw that much torque on the shaft? It s not a maneuver you re ever going to want to do anyway.

Years before I was on another survey sea trial with a heavy handed captain who just pushed the sticks forward. Nothing broke but the boat cavitated and shook for no reason.

 

[madhatter1]

On my 34 that has Cummins i throttle up progressively as even though at 270 HP they produce 735 lbs of torque. Why subject it to full throttle from idle. On the 46 I do the same and once the turbos make boost and they take off I am pulling back on the sticks as they build power to reduce unneeded power to get up to speed. Even after pulling back the sticks I end up at higher than desired RPM and pull back down to cruise.

Anyway we can all run as we see fit. But no way would I do this for a surveyor or run long term at wide open throttle. Seems this should all be discussed with seller, buyer, and surveyor before splash and run. If something breaks seller is stuck with the bill. If nothing breaks buyer ends up with a boat that was just run way harder than normal.

 

[Avenger]

I'm not suggesting hard use as routine operation. I agree a half hour at WOT may be excessive, which is why I stated to check the manual.

However, when you're out trolling and one of your less seaworthy passengers loses their balance and falls on the throttles the shafts are going to be subjected to all that torque whether you consider it prudent or not. It has to be able to take it, and it's supposed to be engineered to do so.

 

[rsmith]

Plenty of people hit stuff and run aground with no drive train failures except bent props. I don’t see a problem with pushing the throttles up in forward. My main gripe is ham fisted people going from forward to reverse without stopping in neutral to let the props spin down. I see a guy with both hands on the clutch levers I just grit my teeth

 

[SKYCHENEY]

Did you mechanic suggested reving up the engine and dumping the clutch?

No. That's not what I said. My point was 30 mins at WOT on a DD should never be a problem as long as the cooling system is maintained.