survey questions

[labrador]

Had a survey and sea trial on a boat I have a contract on this past weekend in Daytona Beach. Engines are Cummins 330bs with 1350 hrs, WOT supposed to turn up to 2800 rpms. Ran well however mechanical guages on the bridge scared the piss out of me as they were approaching 200 degrees after only 1.5 minutes of running on the pins. Surveyor shot the engines with an infrared temp gun and both were right on 180 degrees. Thats ok with me however what do y'all think about the gauges and what is the fix? In addition could only get 2750 rpm with 1/3 fuel and 1/2 water. Had 2 lard asses, me and the hired captain, and 3 other adults approx 150 lbs ea for a total of about 1000#s however the boat has SOOOO much crap on her that I would guess there is another 1500#s extr on board. every nook and cranny on the boat is completly full of extra parts,junk, food games,etc. Hull and running gear was clear of barnacles but had a slime on both. What do y'all think of only getting 2750 insteat of 2850 plus. Something to be concerned about seeing all that weight? Getting results of oil analysis tomorrow.
Skip

 

[MikeP]

Elec helm gauges are not known for their accuracy. But depending on how the temp gun was used, I might not trust that either. It should have been used to shoot the thermostat housing(s) and from the same distance (ideally 3-4 inches, no more) and angle for each measurement. The type of material the housing is made of can affect the temp gun reading as will the color of the housing - you can get more than a 15 degree difference just based on the difference in surface reflectance. A mechanical water temp gauge is a more reliable way to determine the actual water temperature but it's not likely a seller is going to let you/your mechanic install one just to check that.

But if the mechanic was careful with how he took the temp gun readings, I'd be inclined toward thinking they were "close enough".

 

[REBrueckner]

Ditto on MikeP's Post.....and 100 RPM one way or the other is insignificant especially given your description of extra weight.

My Hatt 48 YF with 435HP 8V71TI's ran at about 2150RPM instead of 2300 RPM due to slightly oversize props, I'm pretty sure.,...likely a weight issue in an older boat. Because I almost always ran at only 1500 rpm I liked have slightly oversize props....

 

[Carver370]

If this is on a 41 Maxum (which I think it is from a previous post) the gauges on these boats are notoriously awful. I have 2 friends with a 41 SCA and a 46 SCB and they both needed the temp and tachs changed out when they bought the boat. The company that makes the "Maxum" gauges will rebuild them for about $50 and they will be good as new.

I would seriously look into having a different tach hooked up to the engine to find out the actual rpms and the actual temp.

 

[saltshaker]

The low WOT RPM's may very well be from all the extra gear on board. You'd be surprised how fast that stuff adds up. The bigger question is how did the owner run the boat? If she has been run at a fast cruise and overloaded, then the engines may be a bit more worn out than the hours suggest. These engines do not do well when overloaded. A thorough engine survey may be money well spent.

 

[labrador]

Mike P. the surveyor says he shot the thermostat housing from 2 to 3" away on both engines and that there was no more than 2 degrees of variation on the engines, between 180 and 182 which I think is just about perfect however if i'm wrong, please let me know. Have notified the broker that the gauges are unacceptal and must be replaced along with several other items.

 

[MikeP]

As you describe it was done, my opinion is that the actual eng temps are OK.

The boring cr@p that follows can be ignored:

But the thing to really be aware of with temp guns is what they are telling you is the surface temperature (as they perceive it) of the item in question. They are extremely accurate, if used correctly, at measuring the CHANGE in temp of anything. SO if the gun says the temp of a thermostat housing is 180 now and was 175 a few minutes ago, you can bet money that the change in temperature was 5 degrees. BUT you cannot be sure that the temp itself is correct.

The other thing to remember in this case is that it is measuring the surface temperature of the thermostat housing. But what you are really trying to measure is the temperature of the water INSIDE the housing and it cannot read that. Only a sensor placed in the water stream can do that. And that's why sensors ARE placed there and not just mounted against a housing. Of course, you also have to deal with the accuracy of the sensor/electrical connections/gauge. So a mechanical thermocouple/gauge is the most accurate way to measure oil/water temps.

Admittedly, if the gun is used as your mechanic did, and the material being "shot" is a fairly common material AND if painted, the paint has an average reflectivity, the "error" will be close enough not to make any meaningful difference. But different materials in the same water stream can produce dramatically different temp readings. For example, a chrome pipe, a black rubber hose, and a white cast iron section all with the same temp water running through might show a spread a much as 20 degrees.

 

[GJH]

Did the surveyor hook his own optical tachs up to the engines themselves? The good ones do not rely on the boat's gauges for anything. Was there a haul out done and the bottom and running gear clean? A little fouling can make a 100 rpm difference easy, it does on my boat for sure. My helm temp gauges are pretty accurate, but I still double check them with an infrared during ER checks.
I rely on the mechanical gauges in the ER to tell me what true engine and drive oil pressures are.

 

[GJH]

Amazing stuff. All the resident Ex-spurts have rendered their opinions and no one asked what type or size boat. ROFLMAO

We didn't ask because he already told us in another thread!

 

[saltshaker]

Amazing stuff. All the resident Ex-spurts have rendered their opinions and no one asked what type or size boat. ROFLMAO

It's a 41' Maxum Sedan with Cummins 330HP 6BTA's.

 

[MikeP]

COOL! I always wanted to be an "Ex-spurt." Now I are one by decree!

 

[REBrueckner]

"All the resident Ex-spurts have rendered their opinions and no one asked what type or size boat. "

Makes no difference...but IS nice to know....because someelse may have the same rig.

if the engines only turned say 2000 RPM something is wrong...If they run at 200 degrees something is wrong....in any type or size boat....even a barge...

 

[labrador]

Yes George, she was hauled and bottom and running gear was clear of barnacles but had a slime on the bottom. I would think this in itself might have contributed to not making 2800.

 

[labrador]

By the way, I'm also an R. Smith but go by Skip. I asked this group because I value your collective opinions and do not think that someone who calls Y'all ex-perts in a demeaning way should in any way be confused with me! Rsmith the least you could do is change your name.

 

[rsmith]

By the way, I'm also an R. Smith but go by Skip. I asked this group because I value your collective opinions and do not think that someone who calls Y'all ex-perts in a demeaning way should in any way be confused with me! Rsmith the least you could do is change your name.

Not likely that would take me off the terrorist watchlist. Hang around here long enough and you'll fine out who knows for real and who's opinions dont hold water.

 

[rsmith]

COOL! I always wanted to be an "Ex-spurt." Now I are one by decree!

Imho your one of the "experts" on here.

 

[rsmith]

It's a 41' Maxum Sedan with Cummins 330HP 6BTA's.

And he's on a Hatteras site because?

 

[saltshaker]

And he's on a Hatteras site because?

He had a 40DC and has been looking at other Hatt MY's. Once a HOFer always a HOFer. I'm trying hard to be a member with a Hatt. Feeling out of it since I sold mine. I think my wife and kids will kill me if I don't have one by the spring.

 

[rsmith]

He had a 40DC and has been looking at other Hatt MY's. Once a HOFer always a HOFer. I'm trying hard to be a member with a Hatt. Feeling out of it since I sold mine. I think my wife and kids will kill me if I don't have one by the spring.

Well that explains it. I was thinking a Maxum was a large condom.

 

[saltshaker]

Well that explains it. I was thinking a Maxum was a large condom.

I used to own a Trojan