Eiremar Repower - Cummins Techinician Inspection Punchlist

[Vince Luciani]

I had my pre-launch inspection today by the Cummins technician. Everything went very well thanks to all the guidance obtained here. My punchlist is very minor which is a good thing. I would say to anyone contemplating repowering and doing the work themselves, use the search function of this site (and the old one) and review all the posts and you will get good sound guidance. What a great resource!

The Cummins tech had never seen the port side crossover exhaust and he is a little concerned about the heat and the temperature of the intake air because of the influence of the uncooled section of the exhaust. We will check that carefully during the sea trial/inspection. Cummins has a maximum temperature differenial of 30 degrees between ambient and intake temperature. He would like me to install vents/louvers (4”x12”) on the outboard side of the engine boxes. They would draw air from the cockpit area.

One item that he strongly suggested (not a Cummins requirement) is that I install a fitting on my packing gland and connect a water supply feed hose from the supply side of the raw water pump. He said that the speed of the boat will suck all the water from the packing gland area and the gland will overheat. Anyone ever hear of this? It makes sense to me. How much pressure does that raw water pump put out? Any recommendations on hose type?

Thanks for everyone’s help. I’m getting close to splash date.

[CaptPatrick]

He would like me to install vents/louvers (4”x12”) on the outboard side of the engine boxes. They would draw air from the cockpit area.

Vince,

In a word: DON'T!... Unless you want the noisiest cockpit on the water. Where air can enter, sound can exit. Aslo another area that water can will find it's way into your engine spaces... Side induction air systems are the best way to get free air to the engines, but at this stage of your project, that'd be a considerable retro-fit.

I can't recall the HP rating of your engines, but you need about 75 additional square inches of free air delivery per engine for the Cummins on a B31. Try to gain that much by enlarging the vent holes in the two partial side bulkheads aft of the engine space shelves.

A lot of free air can be drawn around the existing side panels, without modification, as long as that air has an unobstructed path into the engine spaces.


Remember: Where air can enter, sound can exit.

He said that the speed of the boat will suck all the water from the packing gland area and the gland will overheat.

That may be true on some boats, but with the stock stuffing box setup of a B31, from the factory, I don't think this would happen... A flax packing gland functions by squeezing down on the shaft and not allowing water to flow into the boat. Tapping engine water into the boxes inboard of the flax is meaningless. Tapping in after the flax is only throwing water back into the ocean through a different channel. There'd not be enough volume to offset the potential void of water being pulled out of the shaft alley. Tapping in at the flax seal would only result in pushing water against a brick wall.

Water taps to the shaft alley are really only necessary for dripless seals, like the PSS-PYI.

I think you glassed in tubes on your boat, if memory serves me. If you cut the lower tube flush with the hull, and didn't overly extend the inboard length of the tube, you should be OK.

Br,

Patrick

[Vince Luciani]

Capt Pat,

I hear you loud and clear! I am curious as to what you mean when you say "at this stage of your project, that'd be a considerable retro-fit". Can't I install the side induction system now? I don't believe I will have any interferences. I do plan on enlarging the vent holes in the two partial side bulkheads aft of the engine space shelves.

I did glass in tubes on my boat and I cut them flush as you had suggested. I thought the recommendation to feed water to the packing gland was strange. I have never run into anyone who has had that type of setup. I've heard of grease fittings, but not a water supply. I'd much rather do wihtout that extra hose to worry about breaking!

Thanks immensly. I knew you'd give it to me the straight.

[Rickysa]

Vince,

Please allow me to second Capt. Pat on the outboard box louvers...during our repower (Bahia Mar w/ Cummins) the yard put louvers in the side panels beside the engine boxes as well as the aft section of the boxes themselves (for "staion wagon" effect).

Loud wasn't the word...we measured the dBs, and although I can't remember the number...it was up there.

We took the boat down to Pat (from NC) for him to install his air boxes and rework the engine boxes, just because of the noise (and who am I kidding...we were looking for a cool road trip anyway)

Rick

[CaptPatrick]

Vince,

By the reto-fit comment, I only ment that installing an out side air system is much easier done back in the early stages of engine compartment design... Glassing up boxes while working over & around installed engines is a real pain in the butt. Not to mention containing all the fiberglass dust from intruding into every nuck & cranny of a finished engine space.

As UV, and others of us are fond of saying:

Anything is possible with time and money...

Thanks for the "Been There, Done That" comment, Ricky. You were exactly who I was thinking about when I typed DON'T!

Br,

Patrick

[Vince Luciani]

Thanks again guys for steering me on the right path! Ricky, I appreciate the feedback.

I know what you mean about working in tight spaces. I've got bruises on my body from squeezing between the engines and the side of the boat.

Capt Pat, I've got no choice but to do the side induction the hard way. I'll figure something out. Looks like I'll be putting my fiberglassing skills to the test.

[In Memory of Vicroy]

Vince, ditto what the Capt. & Rickey said, no opening in the engine box, use Soundown and get the air from somewhere else - you can pull a lot of air out of the cockpit side panels as Patrick points out. I have the 6BTA 250s and have two clamshell vents on each side thru the hull and they work fine with another clamshell glued on the inside of the hull to keep the spray from getting too frisky. Patrick's side air induction vents are far and away the best.

The suggestion that you plumb pressure water to conventional gland packings is pure b.s. - be wary of this guy. He must have seen problems on a 60 kt Howdy Boat, our boats will never suck the water out of the packing, think deep v.....we got a lot of hull in the water at speed. His worry that the port crossover pipe is gonna heat the intake air up too much has a little more credence, but some fiberglass blanket material should solve that, if its even a problem. Remember, this tech probably has never seen a B31, does not understand how they work, and is comparing Blublines to apples....

UV

[Vince Luciani]

Thanks Uncle Vic. I may try your type of setup before I commit to the side induction system. One of the hardest things when working on the boat is trying to figure out who knows what they are talking about and who is full of BS. Thankfully, when you come to this site you always get the straight scoop!

[scot]

I don't have any first hand experience on 31's with glass stern tubes, but water injected packing systems are very common. If the tubes are very close tolerance to the shaft, or extend too far into the hull water injection for additional cooling "could" be needed. I would not automatically consider the tech a crack head for making the suggestion.

I own a 25 kt boat right now that requires one. In certain cases a boat can simply "run away" from the water that needs to be cooling the shaft and packing. Most boats with prop pockets that incorporate the pocket all the way to the shaft log need them.

It's an easy check. If you can't keep your hand on the packing gland nut at cruise speeds....it's too hot and will fry your packing in short order. They need to drip just a bit.

As has been stated, the PSS-PYI systems are the best solution all the way around.

[Bruce]

30 degrees between ambient and intake temperature

Recheck his explanation of this.

That engine will reach 180 degrees and thus heat the surrounding engine box air.

The incomming air flow will be only as much as the engine requires.

If he believes that an 80 degree outside air temp should only rise by 30 degrees max, that would put the engine room at 110 degrees max.

Not gonna happen unless you put high flow circulation blowers to remove the air.

When idling the air flow is at its least and the temp inside that box will be way above 110.

Sounds to me you got someone who by suggesting that you install vents that has been stated will allow tremendous noise out, rode the short bus to school.

[Vince Luciani]

Bruce, I thought the same thing when I initially heard about this requirement. I sit on those engine boxes and I know they get hot. However, this is directly from the Cummins Installation Manual:

"The air inlet location, air piping, and engine room ventilation must be designed so the air inlet temperature measured at the turbocharger or air cleaner is not more that 17 degree C (30 degrees F) above the outside ambient temperature at rated load and speed. The maximum air intake temperature should never exceed 52 degrees C (130 degrees F) under any operating conditions".

It is what Cummins defines as a "requirement" not a "recommendation".

I think this is the requirement he is referring to. I beleive in the sea trial the tech will be strappping a thermometer to the air filter.

Anybody go through this with Cummins?[/img]

[nic]

Vince,

We used to get this sort of thing all the time from engine manufacturers, particularly European. When we wouldn't buy their engines because of this nonsense they came up with a "tropical rating" and everyone was happy.

I believe it has more to do with giving them an "out clause" when the new boat doesn't go as fast as the new boat salesman promised it would and the factory/shipyard looks to the engine supplier because the props are wrong because the hp is low because.... the air is hot.

Fit good exhaust-lagging & blankets to the turbo, they didn't come standard with our Yanmars and there was a noticeable difference when we fitted them which could only be cooler combustion air which is more hp.

We are about to retro fit the Captain's air-induction boxes and if it is too tight with the engines in we'll have them out in under two hours.

Follow the concensus on this site and you're not going to have a problem.

Nic

[Bruce]

I guess I need to revise my reading comprehension on your first post and retract my first statement.

I glanced over the part about the crossover being non cooled, and crossing near the intake with temps approaching 1200 degrees, the tech is right to be concerned.
My apologies to him.

If I saw that, I would take an air measurement also.

Hopefully you had the pipes wrapped and sealed instead of using blankets.

[Vince Luciani]

Bruce,

The technician was concerned when he saw the pictures before he even arrived at the boat. He said he never saw one done that way before (crossover riser). In the pictures I sent him, the crossover was not wrapped. That really got him concerned. When he arrived at the boat and saw the blanket wraps he felt better about things.

Of course I've been running all this by Tony Athens (he made the risers for me). My risers are not wrapped. They have the blankets. Tony says everything will be fine. Like Tony says, the surface of the wrap gets no hotter than the valve covers. Good point! The crossover should have no effect on air temperatures (at least no more than the heat from the rest of the engine).

I'll find out soon at the sea trial if everything is OK. I'll keep everyone posted.

[JK]

Vince-

I happen to know at least two guys local to you that can lend a hand installing the side air vents. Took us about a day to do both sides. Neither Luke or Buddy care about cutting into a boat as long as it is not theirs! Infact I think they enjoy it...

--JK

[Vince Luciani]

Thanks John. I know what you mean about cutting into the side of a boat. I'm going to explore all options before I make that commitment. I'm in the final stretch now with the repower. It's been a long road, but I don't think I'm telling you something you don't already know!

See you on the water soon. (I hope?)