Cummins in a boat?

[EGaskamp]

This may sound like a really dumb question, but here goes. Has anyone ever considered putting a Cummins in a boat? I have always been obcessed with 2 things, Cummins, and boats! I know it wouldn't be the fastest thing but it would pull. And can you imagine seeing peoples faces when you let out all that smoke from a 12v off a big Baja or something! I know the weight issues can be figured out because in those Bajas and Formulas they are always putting twin 502's and such and I know that weighs more than a Cummins. I just thought it would be awesome! Let me know what yall think or if you know of anyone who has done this. Just remember Cummins guys, just say no to 6. 0!

 

[HoleshotHolset]

TDR member JLeonard has a boat with twin Cummins 6BT's (270hp each).



Remember - you can't take an OTR (Over The Road) engine and just slap it in a boat... you gotta get it balanced first.



Matt

 

[JLinder]

TDR member JLeonard has a boat with twin Cummins 6BT's (270hp each).



Remember - you can't take an OTR (Over The Road) engine and just slap it in a boat... you gotta get it balanced first.



Matt

Depending on what you put it in, it could be the wrong rotation also.

 

[JLEONARD]

you can't take an OTR (Over The Road) engine and just slap it in a boat

Yes you can. This is done often. There is a company in Texas that sells the parts necessary to marinize a Dodge CTD. www.hsmarineservices.com

Check them out.

Depending on what you put it in, it could be the wrong rotation also

True, but if the boat is a straight inboard, this is easily dealt with. ALL the modern marine trannys can be used in either rotation. In other words you can put 2 standard rotation engines in and have counter rotating props.

When I re-powered mine with a single standard rotating Cummins I removed a counter-rotating Perkins diesel. I replaced the transmission with a modern one (wanted all new) so I could still use the RH prop I had.



Converting a gas engine boat to diesel is a nice project but it does require some extra thinking... . you need to make sure the prop shaft, transmission, etc can handle the extra torque/hp. That also probably means a larger diameter prop, so you may have to lower the shaft to get clearance to the hull.





If you are serious bout doing this I suggest you poke around in www.boatdiesel.com It is an awsum site for marine diesel knowledge.



If you need help along the way feel free to e-mail me at -- email address removed -- and I'll try to help.

I can also give you the formula for figuring shaft diameter.



Sounds like a nice project. Good luck.

 

[HoleshotHolset]

Jay - so you're telling me that I can take a bone stock 6BT and just bolt on some stuff to make it seaworthy?



Whatever happened to the need to have them finely balanced, etc. ?



Matt

 

[nutter3]

3 cummins jet boat

there's a guy up here in Talkeetna that has 3 cummins in an aluminum jet boat. his other "big" tour boat has 3 454's. They are impressive baots.

 

[JLEONARD]

Matt,

I never heard anyone talk about doing any special balancing on a diesel engine... . I think there is a different harmonic balancer than the standard Dodge truck version, some of the internal parts are a little different, and the injection pump is set up a little differently (I think 98Rammer ran into this on his truck), but most are to optimize the power curve and handle the extra duty cycle.

I have read that if you keep a conversion engine limited to about 270 hp, the engine will perform well and longevity shouldn't be an issue.

As in towing,

And remember that 270 diesel hp replaces a lot more gas hp because the torque is so high.

For example, my next door marina neighbor replaced twin gas 260 hp V-8s with twin Yanmar diesels rated at 170 hp each. He retained about 95% of his cruising speed (for 25% of the fuel consumption).

Not bad

 

[EGaskamp]

I know that you can put them in the big curisers but I'm talking about a reagular boat like a baja or something. Just for the hell of it. Does anyone have any pictures of this, or web sites?

 

[HoleshotHolset]

Jay:



Thanks for the reply - looking forward to some email in the morning.



Matt

 

[DKupfrian]

The are a couple boats on OffShoreOnly dot com that are go fast diesels. I would like to do it someday. It a popular thing to do overseas as in some countries over there they pay tax based on horse power and not torque. Search that site for "diesel" and weed out the tow rigs.



Good luck!

 

[KMahnke]

Heres some nice links with pics-- Happy looking Oo.



http://www.algroversmarine.com/dieselmenupage2.htm



GOOD INFO http://www.boats.com/content/default_detail. jsp?contentid=12287&WebLogicSession=QTXq1CfTs5c4Xt7gPdjOgO10rgU9e2wAF0ax9gAJbPg051qYrNRr|101964894939520502/170924118/6/7001/7001/7002/7002/7001/-1



Yanmar specs PDF http://www.oldlymemarina.com/engines/yanmar/6LPZP.pdf



Cummins Marine http://www.brownmarine.com/mercdiesel.htm

 

[HoleshotHolset]

Nothing but Yanmars and a couple of CATs... need more Cummins engines on that page.



Matt

 

[bulabula]

I've seen a Fountain 42 with a pair of diesels in it. Had surface drives too. Cruise speed was advertised to be around 60. I've seen new Fountains at the boat shows with triples. But those aren't what most people call "regular boats" either.



Due to the extra weight you need a boat long enough where you can move the engines forward. Hanging a pair of heavy CTD "stern drives" on the transom like you would with a pair of BBC's would probably be dangerous.



I've been on a number of boats with Cummins (not ISB's), but those were displacement hull fishing machines.

 

[WDaniels]

Our inline 6 is naturally balanced as most inlines are.

WD

 

[dpetre]

I had a boat with a pair of 5. 9 Cummins 280HP in it. The boat weight was 24000lbs cruise was 22kt top end 25kt. I sold the engines because I wanted more speed. I need at least 350hp so I am looking for a C series Cummins , CAT, or Yanmar. My goal is 30kt cruise 35 Kt top engine. They sell kits to convert the 5. 9 to marine use. You need raw water pump, after cooler,different exhaust, engine coupler, transmission, some kind of drive, motor mounts and a boat to put it in.

 

[mberry]

I know that you can put them in the big curisers but I'm talking about a reagular boat like a baja or something. Just for the hell of it. Does anyone have any pictures of this, or web sites?

It's easier than you think. I have done lots of research on this myself. Parts can be found all over the place to make an otr motor usable in a boat.



The main thing I found was that since I was going to use a sterndrive setup, the gearing needed to be at least 2. 0:1 in the drive to keep the engine in the power band. You have the torque to turn a much larger and higher pitch prop to more than make up for the higher RPM's of a Hi Perf gas engine. Imco Marine makes drives that are plenty strong enough to handle the torque. Anything is possible if you have the $$$$.



I also thought about using a jet drive. Much simpler that a sterndrive but to handle the torque they needed to be fairly large and not necessarily practical for my application.



My dream was to make a cuddy cabin cruiser type that could keep up with the go fast guys and be much more fuel efficient than them. And of course be a diesel!

 

[JLEONARD]

I need at least 350hp

Cummins makes a B series marine engine that is rated at 370.

My dream was to make a cuddy cabin cruiser type that could keep up with the go fast guys and be much more fuel efficient than them. And of course be a diesel!

Find a hull that is set up for a straight inboard... or a V drive. Adapting it to handle the diesel power will be a lot easier.

Jay

 

[JLEONARD]

1978 Mainship model I... . removed 1 old Perkins T6. 354 160 hp and installed 1 Cummins 6BTA Diamond at 270 hp. Top speed is 18 knots at 2600+, normal cruise is 11. 5/12 knots at 2100.

But the season is almost over... getting ready to haul her for the winter

But then I get to do truck stuff on the weekends.

Jay

 

[Sctt baker]

To convert a 5.9 cummins to a marine 370 first is the 370hp cam next is8.3 marine turbo next is 370 hp injectors next is the pistons need to be from a 24 valve 2000 model 47 to 54 combustion chamber last is p pump metered to 2208col I built one for 5300.00 but I started with a bare block in reality you could build it for 3000.00 in order to put it in a jet boat you need a large pump like a Kodiak 303 or a 273 Hamilton berk or sd309 can not hold the torque the motor produces 724 torque at 2000 rpm 370hp at 3000 the fuel rate is 5.6. Gpm from at 2000 rpm 20gpm at 3000rpm cummins will not tell you the info that I have shared

 

[EDankievitch]

MerCruiser had a Marinized 5.9 a few years back coupled to their Bravo drive system I'm not sure how many parts are left on the shelf but I'd start there for the items you need to put an engine together. Cummins Marine also has the parts but not for the stern drive system.