This forum contains 11 topics and 48 replies, and was last updated by  Tony Athens 6 days ago.

Viewing 11 topics - 1 through 11 (of 11 total)
    • Cummins Marine Forum Topics
    • Repowering a Baja

      This topic has 1 reply, has 2 voices, and was last updated by Tony Athens 6 days ago

      October 12, 2017 at 6:34 am Let me preface this by saying I have not purchased any boat to do this in yet, this is just a really wild idea in my mind that I really want to make happen, and would like some input as to what your thoughts or concerns would be. I am looking at getting a 26-30 foot Baja Sport powerboat if you will, going to get one with a 454 BBC or bigger in it with a Bravo drive to it at minimum. Now I have always been a diesel guy and would love to do a dro…

      Started by:  Bryan Pence


      1 Replies
      Reply #1 November 16, 2017 at 9:59 pm I guess this is another one that got missed.. Sorry.. Before I get into the “has anyone done this” , (I have) let me ask you this……………..Do you have a general “budget” for such a project and do you have a general sketch or some pictures of what you have now vs, what you want to end up with.. That would make it a lot easier to comment effectively.. Tony Tony Athens Seaboard Founder Go here fo…

      Last Post by:  Tony Athens posted: 6 days ago

    • CAT 3126 420 to Cummins 6CTA 430

      This topic has 6 replies, has 3 voices, and was last updated by Tony Athens 3 weeks ago

      October 25, 2017 at 8:26 am Posting this for a guy on down east boat forum. I’ve asked him to join……”hell it’s free” !!!!! “hey bill I know your a cummins guy and are very knowledgeable in this are I’m thinking for down the road I have a cat 3126B 420hp now with a td2.5:1 gear if I put in a recon 6cta 430hp could I use the same gear the cat turns 2800 wot the cummins 2600 wot” The boat is a beautiful 36 H&H down east lo…

      Started by:  Bill Desmarais


      6 Replies
      Reply #6 October 29, 2017 at 12:49 pm Propped right, the 6CTA 8.3 will turn at least 2750 and can run all day at 2400 RPM.. If you are working the motor super easy, just add 1-2″ of pitch to get the R’s down to 2200 or so to get your happy vessel speed. Don’t confuse MINIMUM rated RPM or test cell data with how this engine really likes to be propped in the field under real ocean/working conditions. . Tony Tony Athens Seaboard Founder Go here for the latest stuf…

      Last Post by:  Tony Athens posted: 3 weeks ago

    • Jersey Sportfish Repower

      This topic has 8 replies, has 5 voices, and was last updated by leonaj99 1 month ago

      October 9, 2017 at 6:38 pm The boat is a 42′ 1993 Jersey Dawn III sport fish. The engines are 6-71 TIB’s, 485HP, that have about 1000 hours on them since full rebuilds. They run fine, but they are noisy, dirty, and smelly. It’s a great boat, and my wife and I both love the interior layout and it’s livability. We are now retired and are contemplating the options of running this boat back and forth from RI to FL vs staging it down there and buying …

      Started by:  RicM


      8 Replies
      Reply #8 October 22, 2017 at 8:16 am Rick good luck in your repower and in making the tough decisions. I just want to emphasize Tony’s comments regarding sub system upgrades/improvements. Having done a single engine repower myself in the past and having done most of it myself I found an awful lot to do as soon as the old engine was out. Old thru hulls? Now I have good access so time to install new ones. Old water system plumbing? Gone and a new system installed with proper a…

      Last Post by:  leonaj99 posted: 1 month ago

    • Repower Options ?

      This topic has 6 replies, has 3 voices, and was last updated by Bill Desmarais 2 months ago

      September 1, 2017 at 7:09 am I’m posting this question for a boat owner friend who has a 32 H&H (Osmond Beal down east) lobster boat. Right now the boat is powered by a 1999 Isuzu 6 cyl. Model A-6BG1T 230 hp rated @ 2500 rpms. The engine is keel cooled with dry stack exhaust. Tranny is a ZF63A 2:1 gear, 1.5” shaft with 24X22 #3 cup prop. Weight is a guess @ 12,000 lbs +-. Owner stated the boat is “heavy” for the sea trial. I sea trialed the boat this past week …

      Started by:  Bill Desmarais


      6 Replies
      Reply #6 September 3, 2017 at 8:07 am Rob, I’m confident the repower of this older 32 H&H will be no more than a ReCon engine. 25 Terry Jason down east, 370 6BTA 28 Henriques Sport Fish, twin Volvo 200 41 PA s

      Last Post by:  Bill Desmarais posted: 2 months ago

    • QSC propping to engine load

      This topic has 2 replies, has 2 voices, and was last updated by Luke Nelson 5 months ago

      June 14, 2017 at 6:03 pm Hi Guys, I am after some input on engine load to propping. I have just swapped out a pair of 3208’s to qsc 540’s. I think I may be close but everyone wants more speed if they can have it. The props were calculated on the 490 hp curve to keep within the shaft limits for survey( I am using marinex hs22 2.25). I can post the full numbers but at 2400rpm I get 19.5 knots @ 120 LPH and 52% load. At 2600 I get 22 knots and 74%. The engine …

      Started by:  Luke Nelson


      2 Replies
      Reply #2 June 25, 2017 at 2:56 am Thanks Tony, It makes sense when you say it like that. The sea water sides are on my list to strip and clean. thanks Luke Attachments:You must be logged in to access attached files.

      Last Post by:  Luke Nelson posted: 5 months ago

    • Repower 34' Libby with Cummins QSB 5.9 480

      This topic has 2 replies, has 2 voices, and was last updated by John Albaum 5 months ago

      June 14, 2017 at 9:14 am I’m looking to repower my 34′ lobster boat(Libby 34×13). I have a Deere 6068SFM50 rated at 265hp with a ZF280 at 2:1 to a 2″ shaft spinning a 24×25 wheel at the moment. The engine I’m looking at is a very low hour QSB 5.9 at 480hp. I know the engine will fit and my gear and shaft will handle the horsepower. My questions revolve around the exhaust and the power steering pump that is already on the engine. Th…

      Started by:  John Albaum


      2 Replies
      Reply #2 June 14, 2017 at 10:08 pm Thanks for the reply. With the Deere I can make a little over 19kts at WOT and about 13.5gph, and that’s right were I would like to cruise, so I feel like that wouldn’t be too hard for the 480 to do. I’ve read they can cruise comfortably at 17ish gph. I’d be doing 300-400 hrs per year so not too much. I’ve attached a picture of the engine with the power steering pump attached. I don’t know if this is a Cu…

      Last Post by:  John Albaum posted: 5 months ago

    • Prop Sizing Question

      This topic has 1 reply, has 2 voices, and was last updated by Tony Athens 5 months ago

      May 31, 2017 at 8:56 am Prop sizing. question. These are 6BTA- 300 in a 34′ Hatteras Convertible. 12.5 beam – 26000 lbs loaded (No Trim tabs) ZF220A 1:5-1 gears. 3100 rpm NO LOAD – Current props: 4Blade Nibral – 20 X 19.5 X 1.5 WOT= 2675 RPM – NO BLACK SMOKE UNTIL IT GETS JUST OVER THE 2600 MARK, 2675 WAS ALL SHE HAD TO GIVE. Looking to get 2950rpm. NOTE**Started with props 20 X 21 X1.5 that gave me a WOT of 2600 RPM. The 20 X21 set up…

      Started by:  paul j


      1 Replies
      Reply #1 June 2, 2017 at 7:24 am Paul, These are early 300B’s and they like to spin up easy to well OVER 2900 RPM when your vessel is loaded up as you use it–Typically I say “loaded for bear”…. Basically, you cannot under prop this engine as long as you are happy with the vessel speed at cruise RPM’s in the 2300-2500 RPM range.. Tell your prop guy this—————-Reduce my pitch/diameter/Cup or ??, until the engine …

      Last Post by:  Tony Athens posted: 5 months ago

    • Cutlass bearing

      This topic has 1 reply, has 2 voices, and was last updated by Tony Athens 6 months ago

      April 30, 2017 at 4:11 pm just hat my shaft shortened because when I repowered I had to slide the engine back I needed to replace cutlass so everything was out good time to do it now it’s all back together my question is new cutlass bearing should I be able to lift on the shaft and get any movement 

      Started by:  Derek chandler


      1 Replies
      Reply #1 May 9, 2017 at 8:00 pm All cutless type bearings are “sloppy” as to a shaft fit ,  Maybe a  new 1.5″ cutless is .010-015″ over… If the Bearing is in perfect alignment with the shaft going thru it, yes you can always feel some lift.. As that alignment gets skewed, than is gets less and less.. Another issue is the ID of the strut as to concentricity–Many struts have out of round bores and will crush the bearing as it’s pressed…

      Last Post by:  Tony Athens posted: 6 months ago

    • QSC 540 or C9 565

      This topic has 8 replies, has 3 voices, and was last updated by Bryan 10 months ago

      December 2, 2016 at 4:29 pm So what would be peoples thoughts?  The QSC’s have 4000 hours and the C9’s have 2000 hours. It would be  prop application for around 700 hours a year, both would be propped down to 500hp  and driven for the best part at around 1800  rpm. Discounting the general condition  of the engines would one be seen as the better choice? I had a water ingress incident and have 2 wet 3208’s and it seems the right time to upgrade. I und…

      Started by:  Luke Nelson


      8 Replies
      Reply #8 January 12, 2017 at 5:22 pm <p>Well the early pumps had issues that was recognized by caterpillar in a service letter. I’ve seen heui pumps last for upwards of 6000 hours and others 1500 hours was all the time they lasted this is where strict oil changes and regular maintenance ( anodes etc.) come into play, most times the pump can not make full pressure and the engine runs poorly at higher rpm. The downfall is when the pump fails and contaminates the oil rail …

      Last Post by:  Bryan posted: 10 months ago

    • Repower after swamping

      This topic has 12 replies, has 3 voices, and was last updated by Tony Athens 11 months ago

      November 26, 2016 at 3:03 am Looks like I get to kick off this subject, but before I do, Happy Thanksgiving! Back in June, right before our salmon season was to begin, my boat swamped at the dock.  Long story, but suffice to say it was a disaster.   The boat has been in my family since it was new in 1990.  She was, up until June, powered by twin 6125A Luggers, rated 460 hp @2300 with 2:1 ZF 320A gears.  Anyone familiar with the engines, knows this is actually a ligh…

      Started by:  James Burton


      12 Replies
      Reply #12 November 28, 2016 at 9:36 pm Sorry for the delay getting back, but I had a busy weekend . Controls & MGX Gears—I can see you are way ahead of me and have done your home work.. Very good.. As to electronic controls and the MGX gear—It all comes down to solid support when you need it most—In S. Calif, there is basically only one guy that knows those controls back to front. Yes, as electronic controls go, the EC300 are at the TOP, but at least with GD or ZF, you have…

      Last Post by:  Tony Athens posted: 11 months ago

    • Repowering a 36 Northern Bay with a QSM 11/670

      This topic has 1 reply, has 2 voices, and was last updated by Jerry Farnham 12 months ago

      November 27, 2016 at 4:57 am As started elsewhere this is the summary of a repower of my 36′ Northern Bay Downeast boat from a damaged QSM 11/670 to a reman QSM/670 .   What seemed to at first be a simple plug and play turned into a seemingly endless series of one by one steps.  What was expected to be a 2 week out and in process turned into an almost 2 month affair.   Basics – Skipjack is a 36′ Northern Bay – classic Maine downeast hull.  Fu…

      Started by:  Larry Backman


      1 Replies
      Reply #1 November 27, 2016 at 12:37 pm What/where is the old QSM11? Looks good. The yard should have caught the difference in couplings.

      Last Post by:  Jerry Farnham posted: 12 months ago

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