1972 31 Bertram; 330 Cummins

Wursty · Post by **Wursty** » Apr 1st, '11, 08:42

When drifting in ocean for shark, tuna, tiles how many of you keep motors running versus shutting them down. My concern is getting saltwater backed up and over the risers and into the cylinders. I don't have surge tubes and I'm concerned about getting hydro-lock so for many years I keep them running all day & night so I don't plan to change unless somebody thinks it's too precautionary. Any opinions or comments?

TailhookTom · Post by **TailhookTom** » Apr 1st, '11, 08:44

I never shut my Volvo diesels down unless the docklines were firmly attached! But those who know me, know I am a bit over cautious. Must be why fish love me and women fear me, or the other way around!

randall · Post by **randall** » Apr 1st, '11, 08:45

diesel?......if not i have rubber stoppers from a lab supply house i can put in the exhausts for prolonged open water drifts and anchorages. good to have for an interior exhaust failure....as mentioned recently..."ask me how i know"?

Ironman · Post by **Ironman** » Apr 1st, '11, 10:57

I installed the flappers on the end of the exhaust .. they make 6" I cut down toi 5" .,.. we had the tsunami & a big storm after .. I was on a mooring.., many splashes over the transom,& incoming tides.... Glad I had them . Wayne

Wursty · Post by **Wursty** » Apr 1st, '11, 12:35

I'm just thinking that while drifting and the tendancy of the boat rocking and rolling is it risky to shut down and then risk gulping into the engine sea water? I've been concerned about this and have never taken the chance of shutting down while drifting in open ocean. Where did you get those rubber exhaust flaps and do you think the flaps will work while drifting to prevent hydro-lock?

randall · Post by **randall** » Apr 1st, '11, 13:10

i HAVE the rubber flaps and still managed to get sea water in my port engine. now i just put the stoppers in. takes 10 seconds and turns it into a non issue. i have em on a tether so if i forget to take em out i dont lose em. i leave them in when docked in heavy weather too. less holes below the water line.

Wursty · Post by **Wursty** » Apr 1st, '11, 13:42

Randall, so where did you get those rubber stoppers from? I have 5" exhaust ports and i like your idea and it's simple. I guess it's like a rubber cork...your direction as to where to buy is appreciated. thanks,

mike ohlstein · Post by **mike ohlstein** » Apr 1st, '11, 14:20

http://www.mcmaster.com/#catalog/117/3725/=boud4u

Measure the ID of your exhaust.

Item # 9545K87 might just fit.

Wursty · Post by **Wursty** » Apr 1st, '11, 15:15

Mikle, thanks for the info...I'll measure tomorrow an order if it's the right size.

randall · Post by **randall** » Apr 1st, '11, 15:45

that'll work...i got mine from a laboratory supply. they are meant to go on large glass containers. i put a screw eye in each one and a tether and clip so i can just attach the whole shooting match to a d ring on the transom. if you are ever off shore and have a catastrophic failure of your exhaust they will seem like a pretty good idea.

Tony Meola · Post by **Tony Meola** » Apr 1st, '11, 21:24

Try a plumbing supply if you need one bigger than McMaster has. Maybe Bruce or Capt. Pat will jump in but if you have mufflers, I think it is a little harder for the water to get up the risers.

bob lico · Post by **bob lico** » Apr 1st, '11, 23:59

i shut down one or both engines quite frequently and always trolling using one. i alternate engines to keep hours equal . i have mini max mufflers which have a one way shield on inlet and exhaust are up and over no need for surge tubes.

Marshall Mahoney · Post by **Marshall Mahoney** » Apr 2nd, '11, 15:45

I'm worried about the same thing and was thinking about installing in-line check valves closer to the engine. I don't think they would have too much back pressure. Any opinions in check valves??

bob lico · Post by **bob lico** » Apr 2nd, '11, 18:41

when in the canyon on a overnighter i stop trolling a hour or so before sundown and do the high flyer circus act . shut engine till following morning. generator runs overnight while chunking. i have total confidents in the system even in gale warnings near shore.

Sean B · Post by **Sean B** » Apr 3rd, '11, 19:43

Nerf footballs work pretty nicely. I changed out some exhaust hose last spring and the nerf balls sealed the exhaust completely, and are easy to work in and out. At your local Toys R' Us

Whaler1777 · Post by **Whaler1777** » Apr 3rd, '11, 19:50

Are you guys talking about leaning over the transom of the boat and plugging the exhausts while out in the canyon?

Tony Meola · Post by **Tony Meola** » Apr 3rd, '11, 20:51

Whaler1777 wrote:Are you guys talking about leaning over the transom of the boat and plugging the exhausts while out in the canyon?

John

Unless you know a way of doing it from inside the boat, hanging over the transome is the only way. Just make sure Uncle Vic isn't standing next to you doing his thing off the transom.

One more thing, don't forget to pull them out before you try and start her up.

Whaler1777 · Post by **Whaler1777** » Apr 3rd, '11, 21:28

Gotcha...

randall · Post by **randall** » Apr 4th, '11, 08:12

One more thing, don't forget to pull them out before you try and start her up.[/quote]

hence the tether....i've forgotten more than once.

in an emergency a styro coffee cup will work........ask me how i know!

jspiezio · Post by **jspiezio** » Apr 4th, '11, 10:37

Honestly, with thousands of hours offshore on boats, I have never done this and never had a problem.

Charlie J · Post by **Charlie J** » Apr 4th, '11, 11:39

ive used the styro cup when i had to work on my fiberglass elbows years ago

Wursty · Post by **Wursty** » Apr 4th, '11, 14:54

My set up is 5" exhaust pipe with inline Vernatone mufflers with a 11" x 30" body. I have a geni so shutting down is a good option as long as those Cummins don't ingest seawater while drifting or anchored. As I said before that I've never tempted to shut them down while offshore but it's good to hear everybodies opinions and techniques. It's all about "the faithfuls" experiences. Thanks,

JP Dalik · Post by **JP Dalik** » Apr 4th, '11, 16:09

The Centek mufflers that you have are baffled, I would feel more secure if you had surge tubes.

We have 330's with 5" elbows that dump down and across (in the port motors case) into 6" exhausts with surge tubes, the mufflers in our system are Centek Centubes @ 6". To date there have been no issues while anchored or drifting. From time to time we do fish in sporty conditions on the hook. I believe that the B31 with Cummins installed have the elbow just about 11-13"s above the water line, this is right on the cusp of a correct installation. The surge tubes are just a little more insurance.
Primex builds a marine exhaust piece with a check valve in it. But I believe it was pricey.

Good Luck

bob lico · Post by **bob lico** » Apr 4th, '11, 17:29

jp the 6" mini max muffler has a full cone on the entrance . i used 6" all the way from sprinkler head down thru 70 degree fittings . as you know when drifting in the canyon at night you can take a enormous wave opposite the normal wave action from a passing monster tanker or container ship. lift the stern way in the air and comes down with engine shut down all night . what more of a test could you possibly make. this up and over exhaust with full 4" pipe and the rest of exhaust system definitly does the job . not to disagree but the mini max does the job.i had numerous 8' waves slam into trasom. if the shoe fits wear it.

JP Dalik · Post by **JP Dalik** » Apr 5th, '11, 00:47

Bob what are you disagreeing with:

The fact that the OP (Original Post) mentioned the owner has 5" Centek Vernatone mufflers and is concerned because he doesn't have surge tubes

or

The fact that the system I discribed in CHIMERA is not in fact operational and installed as stated.

The OP didn't mention anything about changing mufflers to something "else" or adding surge tubes. My opinion is that as the system sits and was described I would be hesitant to shut her down in sporty conditions. We are not talking about your boat but comparing other installations and success or failure with the OP. I believe that is what he was looking for.

jspiezio · Post by **jspiezio** » Apr 5th, '11, 10:10

Primex builds a marine exhaust piece with a check valve in it. But I believe it was pricey.

Jp, I just re-read your post. This seems like a good idea.

bob lico · Post by **bob lico** » Apr 5th, '11, 13:11

when a 31 bertram has a genset generally there is only a short distance left to the installation of a surge tube . some of us have waste tank on opposite side leaving no room for surge tube. after examining all mufflers i decided on centek minimax 1050500 in 5" or 1050600 in 6" because of the unique cone to stop a surge of water moving forward in conjuction with a exhaust that goes 90 degrees and then straight vertcal before the muffler . this puts exhaust height about 1" under engine hatch at least two foot above water . this may not help original post but serves to help anyone in this staged while building a 31 bertram . for a existing boat like the original post use 1200377 centek part number for check valve or inexpensive thru hull with internal flapper 1200342 comes in white or black these numbers are for 5".

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1972 31 Bertram; 330 Cummins

1972 31 Bertram; 330 Cummins

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