Perkins 4-108 in a 10,000 lb. boat

Ross · Aug 6, 2009

My ten HP engine will push my Islander 30 (about 9500 pounds) to about 5.5 knots with no complaints after that I just start digging a hole in the river and at about six kts my cockpit drains back flood.

BobM · Aug 6, 2009

C'mon Hermit...get the lead out...you can't afford a new roller furler, but you can afford to put a ridiculously large engine in? It's a sailboat!

BobM · Aug 6, 2009

Ah ha...

...I hadn't seen your about low oil pressure yet. Apologies! I'd still fix the furler if the engine is running okay. Then keep you eyes open for a spare engine. Plenty of people repower and remove these 1 cyl yanmars.

sailaway78 · Aug 6, 2009

4-108

Hermit,
The 4-108 is a beast. Big, and heavy. I don't know if there is any way you could shoe horn that thing in the space where a one lunger was, but IMHO it is far to heavy for any 30 footer. Of course, if you can get it in there, can probably water ski behind it.

Joseph Shirley · Aug 6, 2009

I also think it's too much engine. Not because of the power, because you can have a motor sailor if you want to; but with that much weight, your tail is going to be dragging big time. The sailing performance will suffer.

Joe S

Snotter · Aug 7, 2009

Generaly speaking, the more the cylinders the smoother the engine runs. Also, raw horespower is nice for pushing through waves and wind. However, pay attention to whether the engine would sink the boat below the designed waterline. Larger engines also consume more fuel, requiring larger fuel tanks. Sailing is one big compromise.

Maine Sail · Aug 7, 2009

Hermit

Hermit that engine would be unnecessarily large for the C-30 and you'd most likely never be able to run it at 80% thus not utilizing the potential. The main reason this won't work well is SPACE. The C-30 requires a low engine to fit under the cabinet and settee and it also can't be very long altogether. The 4-108 is quite large. I installed a Universal M3 20B in mine and I know the M25's fit as well. Even then we still ahd to make some height modifications to galley cabinet for the exhaust riser. 15- 23 hp is more than enough for a C30.

Heck there are still many C-30's with the one lunger doing just fine, when the prop is right. Make sure your current engine can turn max rated RPM with a clean bottom & prop. If you can't get your engine to MAX rated RPM or it gets there too easily or goes above it the prop needs addressing.

The MAX RPM on our boat is 3000 RPM and the engine gets to 2980 as measured with a digital photo tach. It took two tries with the prop manufacturer to get this just right. The first one came in 270 RPM to low. The second one is just about perfect and only off by 20 RPM which is about as good as it gets. Your engine should be able to deliver MAX RPM no more no less within 50 - 75 RPM for the best results.

zeehag · Aug 7, 2009

Maine Sail said:
Hermit that engine would be unnecessarily large for the C-30 and you'd most likely never be able to run it at 80% thus not utilizing the potential. The main reason this won't work well is SPACE. The C-30 requires a low engine to fit under the cabinet and settee and it also can't be very long altogether. The 4-108 is quite large. I installed a Universal M3 20B in mine and I know the M25's fit as well. Even then we still ahd to make some height modifications to galley cabinet for the exhaust riser. 15- 23 hp is more than enough for a C30.

Heck there are still many C-30's with the one lunger doing just fine, when the prop is right. Make sure your current engine can turn max rated RPM with a clean bottom & prop. If you can't get your engine to MAX rated RPM or it gets there too easily or goes above it the prop needs addressing.

The MAX RPM on our boat is 3000 RPM and the engine gets to 2980 as measured with a digital photo tach. It took two tries with the prop manufacturer to get this just right. The first one came in 270 RPM to low. The second one is just about perfect and only off by 20 RPM which is about as good as it gets. Your engine should be able to deliver MAX RPM no more no less within 50 - 75 RPM for the best results.

having just muscled into my formosa a beautiful and HUGE perkins 4-108, i would say--please fix the engine you already have or find a small yanmar--2 cyl work fine--i have one in my ericson 35---there is NOT enough room in your engine room for al the misc bs a 4-108 needs to have for complete installation, nor is there any room for checking oil whenya are done with the install....goood luck--a 2qm15 is perfect for your c30....i swears...btw--a perkins 4-108 weighs in at 600 pounds..yannies are a LOT lighter in weight----.

Stu Jackson · Aug 7, 2009

Hermit, just for comparison sake, the original Catalina 30s came with Atomic 4s (gas, HP was larger than the initial diesels which followed, but I forget exactly how much) - which were then replaced with 11 hp diesels, and then, over the eyars, built up from 11 to 21 to 23 to maybe 30 HP. Even the 11s moved the boat just fine. We have a 21 hp M-25 in our 1986 C34 and it works just fine for moving the boat. The history of C30 "powerplants" is most likely on their Association website. Good luck in your search. What's up with your SAILS & SAILING?

zeehag · Aug 7, 2009

Hermit Scott said:
I will pass on the engine. There is a 2qm available right now. but I don't know how much an improvement it would be over the ysm12. Does any oone know if a 2qm will get it up to hull speed?

A 2qm has to be quiter than the ysm. With out the compartment coevers and cushions in place it sound like a tool box full of wrenches rolling down a hill.

Zeehag=do you have a 2qm on your ericson 35? If so what speed will it go and what does the boat weigh?

..

my 2qm20h is a good engine--makes on my boat only 5 kts but i have wrong prop--with correct prop should be fine...2qm20h is an awesome engine---you would do very very well with any q2m engine-even a 2qm15-----awesome engines.......just make sure ye have the correct prop !! boat is 11,600 pounds.....