Is 315 HP enough?

[ohiohatteras]

I'm still on my endless crusade to re-power my 1976 36C with diesel's on a budget because I'm not independently wealthy!
Found a deal on some rebuilt, with warranty, 315 HP Yanmars. I know the 370 Reman Cummis are the ticket, but they are outta my budget.

My questions for you all.....is 315 HP enough? And by enough, I mean to get a cruise around or above 23-25 kts.
My one buddy says they are due to the higher RPM's they can be run at....

Looking for any an all $.02.....
Thanks

 

[mykim]

I'm still on my endless crusade to re-power my 1976 36C with diesel's on a budget because I'm not independently wealthy!
Found a deal on some rebuilt, with warranty, 315 HP Yanmars. I know the 370 Reman Cummis are the ticket, but they are outta my budget.

My questions for you all.....is 315 HP enough? And by enough, I mean to get a cruise around or above 23-25 kts.
My one buddy says they are due to the higher RPM's they can be run at....

Looking for any an all $.02.....
Thanks

Your going to have to provide more info. IE, what HP is or was in her. Gear ratios, prop sizes etc. Then there are calculations out there that will tell you what to expect from your hull.

 

[Boatsb]

A friend had a series 1 36 with 210 hp cats that topped out at just about 20 kts wot.

He had no generator and 1/2 fuel light water when we did that.

I think they may get 20 to 21 cruise but not over 23. Talk to 34 owners and they'll probably confirm they won't get that speed on their boats either.

 

[Boatsb]

Dr. Jim.

Care to share your setup and results?

 

[Glory]

yanmar parts are expensive!!

 

[jim rosenthal]

Dr. Jim.

Care to share your setup and results?

Sure. I have Cummins 370s, 1.5 ZF gears, 1.5" shafts, and (I think!) 21"x22" four-bladed Michigan wheels. On sea trials she did about thirty knots with a half load of fuel and (I think) four aboard. Possibly 30.5 average on a two-way run, with and against the current. She will cruise 25-26 without difficulty.

The Yanmars are a bit lighter, I think. And they will spin faster; I know mine will get up to rated revs which I think is 3050, but the Yanmars will turn up higher. Now, whether the boat would go as fast, given the limitations of diameter and pitch for the smaller Yanmar, I don't know.

Easy for me to say, but if I were going to do this repower, I would do everything I could to stretch and get the Cummins B engines.

 

[Mike36c]

I repowered mine with the 330b's and 1.5:1 gears, the resulting performance was nearly the same as Jim's. The yanmars would probably work ok in optimum sea conditions or the icw but in plowing into a 20kt head sea at 12kts would be beyond their capabilities. EGT and boost gauges would confirm this. Plus as mentioned the parts are impressively expensive. I agree with Jim, do whatever you can and find a pair of b's or it might be better to keep what you have.

 

[Avenger]

Just a point of information, since Cummins uses metric horsepower to rate their engines a 330B is actually 315 HP.

 

[rsmith]

The stock 36 came with 3160 210 hp cats for the diesel option. They were a solid 18 kit cruise with 200 extra hp you should do better than that if the rating is accurate

 

[jim rosenthal]

Right, and either the Cummins or Yanmars are lighter than the 3208s. I think Yanmar parts are generally a lot more than Cummins, though.

 

[Boatsb]

I don't have enough exposure to yanmar reliability and maintenance costs to speak from experience but the few parts I have had to get were reasonable except motor moubts.

 

[ohiohatteras]

I understand that Cummins are the best engine for the boat if money was no object. But in my case, it is.
I also understand that I should prolly not be looking into diesel repowers due to lack of getting anything back for it, but I've had my boat for 22 years and dont plan on getting another one.

What I could really use information wise is somebody's good, educated opinion if 315HP Yanmars would get the job done?
Thanks

 

[saltshaker]

They should get you there and perform similar to 330 6BTAs. What you need to look at is what gear ratio they have and what props you would need for your boat. Compare that to the Cummings and see if it's still economically feasible. The high Erving Yanmars will allow you to use smaller shafts but you need to see what props will be required with the gears they have. Run the calculations through a good prop shop to see if the engines and gears will be a good match for your 36. How much of a difference are the engines and gears? I'd expect similar cost for either

 

[Kim Beatley]

I've been talking, thinking about re-powering my 36C for 10 years. I currently run 330 HP Marine Power gas engines in my '72. This year they are 23 years old. For the 10 years I have owned the boat, I average about 300 hours per year with an annual average fuel burn approaching 15 gallons per hour. I normally cruse between 18 and 20 knots. The engines will push the boat at 30 knots, when hull is clean and lightly loaded, but boat is not stable at that speed, and I do not even want to discuss fuel consumption at that speed.

Looked at Cummings and yanmar. Reality is, when I do repower, I will likely go right back to a 5,7 liter marine power engine, however rated at 450 HP. You cannot beat the price and do not have conversion headaches. This thinking is based working off a limited budget.

If I had unlimited funds, I would buy new and larger boat!

 

[ohiohatteras]

I've been talking, thinking about re-powering my 36C for 10 years. I currently run 330 HP Marine Power gas engines in my '72. This year they are 23 years old. For the 10 years I have owned the boat, I average about 300 hours per year with an annual average fuel burn approaching 15 gallons per hour. I normally cruse between 18 and 20 knots. The engines will push the boat at 30 knots, when hull is clean and lightly loaded, but boat is not stable at that speed, and I do not even want to discuss fuel consumption at that speed.

Looked at Cummings and yanmar. Reality is, when I do repower, I will likely go right back to a 5,7 liter marine power engine, however rated at 450 HP. You cannot beat the price and do not have conversion headaches. This thinking is based working off a limited budget.

If I had unlimited funds, I would buy new and larger boat!

My boat has Marine Power 454's at 330HP too, but mine are ORIGINAL 1976 models (41 years old) with 1800 Hours. At 3150 RPM's I'm running 16 kts. Mine wouldnt hit 30 kts unless you threw it out of an airplane!
How you getting yours to run so fast...they are pretty much the same boats....???

 

[ohiohatteras]

They should get you there and perform similar to 330 6BTAs. What you need to look at is what gear ratio they have and what props you would need for your boat. Compare that to the Cummings and see if it's still economically feasible. The high Erving Yanmars will allow you to use smaller shafts but you need to see what props will be required with the gears they have. Run the calculations through a good prop shop to see if the engines and gears will be a good match for your 36. How much of a difference are the engines and gears? I'd expect similar cost for either

Jack...the 315HP Yanmar's I found are rebulit with warranty for $25k for the PAIR......
That's less than ONE Cummins reman.....

 

[saltshaker]

Jack...the 315HP Yanmar's I found are rebulit with warranty for $25k for the PAIR......
That's less than ONE Cummins reman.....

Wow I had no idea those little Cummings had gotten that expensive. A friend was quoted 19k each with gears for new ones back when I repowered my 46c in 2002. I wouldn't have thought the remans would be that expensive.

 

[Walter P]

But our government experts claim that we have little to no inflation....give me a break..

Walt

 

[Kim Beatley]

My boat must be propped differently. I have hit 30 knots several times measured with GPS, but conditions are perfect. Only two people on the boat. Leaving boat yard for test run with mechanic, freshly painted bottom, clean holding tank, light fuel load. Mechanic is driving. I am too afraid of tearing something up, running it that hard.

At 3150 RPM, I am running over 20 knots.

Now reality, let the boat sit for 3 weeks in the hot summer, top speed drops off dramatically, 22 to 24 knots.

Had risers replaced last month. Mechanic told me that compression was down in 3 cylinders on Port engine, and 2 cylinders on starboard. Expect to see decrease in performance and I should consider an engine change out.

Luckily, I cannot tell any difference. I am going to run them until Sea Tow comes to the rescue!

 

[Top Hatt Craig]

I've been talking, thinking about re-powering my 36C for 10 years. I currently run 330 HP Marine Power gas engines in my '72. This year they are 23 years old. For the 10 years I have owned the boat, I average about 300 hours per year with an annual average fuel burn approaching 15 gallons per hour. I normally cruse between 18 and 20 knots. The engines will push the boat at 30 knots, when hull is clean and lightly loaded, but boat is not stable at that speed, and I do not even want to discuss fuel consumption at that speed. Looked at Cummings and yanmar. Reality is, when I do repower, I will likely go right back to a 5,7 liter marine power engine, however rated at 450 HP. You cannot beat the price and do not have conversion headaches. This thinking is based working off a limited budget. If I had unlimited funds, I would buy new and larger boat!

Good morning, hp of the 5.7 is shown as 292, is there a turbo available?Horsepower: 292 hp ( 218 kW ) @ 4800 rpmTorque: 370 lb-ft ( 502 Nm ) @ 3200 rpm