Replacement inboard diesel engine required for RT 25, 2012

[sereid]

Ranger Tug 25, 2012
I am having to replace the Yanmar 4BY2-180 after a catastrophic engine failure.
I am trying to determine what new engine in terms of HP will be the best fit for this semi displacement hull for a person who wants to cruise at 8-10 knots.
Also what new engine will require the least amount of modification to fit into the R 25.
Thank you
stewart

 

[Diatom]

Just swapped a 4LV170 into a C26. Needed a new properly-sized thru-hull, anti-siphon protection, some fiberglass/dungeon-step fiddling, and I think it's going to demand a bit of prop-fiddling and potentially a gearbox replacement to properly load the engine (stuck with the original KM40 2.04:1 gearbox for now). As-is it runs at 14.5 knots fully loaded at recommended cruise RPMs. Advantage vs. reman or D3: LV still in production, parts readily available, reman would have been prohibitive considering decrepit cooling system, one bad cylinder, history of seized turbo. Runs smooth, cool, quiet compared to 4BY2-180. Two unexpected benefits: with the engine aligned to permit coolant reservoir inspection port in same-old place, the chronic list-to-port disappeared - in effect increasing trim tab utility (couldn't fully-deploy flanged 12" tabs with the list); and the "firehose" exhaust blast against my dinghy is gone. Only other option was newer/larger boat - and I like the aesthetics, agility and one-handed operation under all conditions of the C26.

Diatom

 

[sereid]

Hi Diatom,
Thanks for the feedback!
I have been told that the 4LV 170 will not fit onto the C25 engine space, but I will take another look at the specs to confirm.
Looks like we might have to settle for a smaller Yanmar 4JH-110 rather, than pay too do extensive modifications.
Appreciate your insights...
Stewart

 

[Seakr25]

Ranger Tug 25, 2012
I am having to replace the Yanmar 4BY2-180 after a catastrophic engine failure.
I am trying to determine what new engine in terms of HP will be the best fit for this semi displacement hull for a person who wants to cruise at 8-10 knots.
Also what new engine will require the least amount of modification to fit into the R 25.
Thank you
stewart

8-10kts … 110hp yanmar will probably do it … 130hp+ will definitely do it. 110 yanmar should fit with minimal work. It would have fit very nicely into my 08 R25 classic , guessing a 12’ SC would also fit well. I ended up putting in a betamarine (kubota) for mechanical simplicity and lead time …. Yanmar was 18 months out at the time I needed one vs 5 with beta. Downside is the beta blocks are larger for much lower hp. I’m stuck at hull speed of 6.5-7.5 but sip 1-1.3gph doing it and that was the speed I wanted anyhow for my boating style and area. See my post history for more info. Also checkout svc scalywags on YouTube and specifically the lady m videos. They repower a boat like yours …

 

[sereid]

scalywags on YouTube and specifically the lady m videos.

Hi Seakr25 Thanks for the input - extremely helpful! I checked out the scalywags video and they did a fantastic job. There is hope on the horizon!

 

[Rode Trip]

Ranger Tug 25, 2012
I am having to replace the Yanmar 4BY2-180 after a catastrophic engine failure.
I am trying to determine what new engine in terms of HP will be the best fit for this semi displacement hull for a person who wants to cruise at 8-10 knots.
Also what new engine will require the least amount of modification to fit into the R 25.
Thank you
stewart

After finally getting to put a good amount of green water and a few blue water miles under the keel of our R-25 I would never under power the boat. I'm envious of the 180 hp that you had as I think the 150 hp is marginal. I found that my boat is very efficient at 6 knots burning 1 gallon per hour. But it needs to be really calm water to be comfortable. When it starts to pick up a little bit or get a little lumpy she's much more comfortable at 2 GPH and 7 knots. If it's still picking up and a bit of roll from a swell, 2.5 GPH and 7.5 knots is even better. When it's really rough and rolly I run it at 6.5 GPH (about 85% load of the 150 HP engine). It's not at all efficient at 10.5 knots (loaded, 11.5 knots unloaded) but it's far more comfortable as the stern squats and is pushing a big wake and almost ready to come up on a plane. Having recently run the 70 miles between Key West and the Dry Tortugas I was so thankful to be able to put the hammer down, burn the fuel, and be able to plow through the seas and cross swell in the rough spots. When it was calm or we were in protected water I ran at the 2 GPH rate. I'd feel extremely limited in the conditions I could comfortably go out in if all I had was a 110 HP engine and stuck in the 6-7 knot range.

 

[sereid]

After finally getting to put a good amount of green water and a few blue water miles under the keel of our R-25 I would never under power the boat. I'm envious of the 180 hp that you had as I think the 150 hp is marginal. I found that my boat is very efficient at 6 knots burning 1 gallon per hour. But it needs to be really calm water to be comfortable. When it starts to pick up a little bit or get a little lumpy she's much more comfortable at 2 GPH and 7 knots. If it's still picking up and a bit of roll from a swell, 2.5 GPH and 7.5 knots is even better. When it's really rough and rolly I run it at 6.5 GPH (about 85% load of the 150 HP engine). It's not at all efficient at 10.5 knots (loaded, 11.5 knots unloaded) but it's far more comfortable as the stern squats and is pushing a big wake and almost ready to come up on a plane. Having recently run the 70 miles between Key West and the Dry Tortugas I was so thankful to be able to put the hammer down, burn the fuel, and be able to plow through the seas and cross swell in the rough spots. When it was calm or we were in protected water I ran at the 2 GPH rate. I'd feel extremely limited in the conditions I could comfortably go out in if all I had was a 110 HP engine and stuck in the 6-7 knot range.

Thanks for that perspective, good food for thought. In an ideal world bigger may be better in the situations you describe but the R 25 has real engine size limitations. The svc Scallywags You Tube video on Lady M refit with a 4JH4 110 shows that they were able to achieve 11 knots on the first sea trial. I appreciate your thoughts!

 

[Rode Trip]

Thanks for that perspective, good food for thought. In an ideal world bigger may be better in the situations you describe but the R 25 has real engine size limitations. The svc Scallywags You Tube video on Lady M refit with a 4JH4 110 shows that they were able to achieve 11 knots on the first sea trial. I appreciate your thoughts!

I wonder if that 11 knots was on an unloaded boat at wide open throttle. Mine can do 16 knots at WOT when lightly loaded, I've seen one with the 180 hp do 18 knots, but when full of cruising equipment and 85% of engine load I was back down to 10.5 knots.