Grand Banks 36

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J

jacsan

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Aug 4, 2023
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I am considering to purchase a GB 36 with a single 110hp engine. Is this too under power for this boat?

Thanks,
Jack
 
Depends. For displacement speeds (7-8 knots), that is a perfect engine. I believe that is a semi-displacement hull, so it is capable of speeds above displacement speeds. I'm guessing it was re-powered.
 
Could be a great engine for that boat if, like most people, you'd stay at or below 8kts. Another 110hp would probably get you to 10kts at 4x the fuel consumption - hard to see when that would ever be helpful.

Also, a single 110 is likely to make your life much much better when it comes to maintenance versus, say, twin Lehman 120's. We have a CHB41 with twin Lehamn 120's and I'd prefer a single, particularly if it had a bow thruster.

One thing someone is sure to point out: if you are going with a single, you'd better make 100% sure it's maintained and tip top condition.
 
We have a single 135. Maybe we use 1/2 of that HP to cruise at hull speed (Just under 7 knots). A single 110 is plenty for that boat. To get a 36 "over the hump" on to plane would take probably 4 times as much HP.....and fuel. If its a well maintained engine it should be a great fit. (Diesel I am assuming)
 
You'll maybe get 7 knots downhill, probably more like 6.5. Pretty old engine.
I have twin Cummins 210 turbos in mine and cruise comfortably at 8.5 knots at 1600 revs.
 
Is it a 110 Lehman, same block as the 120?

Anyway, ask the seller at what rpm they run the boat and what speed it runs. This info will tell us much more. I had twin 120 in a GB36, it did 12
5 at wot.
Don't expect more than 7 for cruise, maybe 9 at wot.
 
I have a single 135 and cruise at 7-7.5 knots at 1650-1700 rpm with a clean bottom. The bottom is key. Fuel consumption is around 1.5 gallons,/hr. Love it. Friend has same boat with twin Cummins 250, with a clean bottom he can do 15:knots. But has not run it at that speed long enough to calculate fuel burn, maybe 25-30.

We leave early arrive on time, and she just purrs. Ours is a GB36; Europa, and for sale!
 
It should be fine if you like a 7 knot cruise. I like to cruise faster than that but that is just my preference. Have you actually cruised at 7 knots for several days? If you have and liked it then great. If you haven’t then try it before you buy because you may be like me and not be happy at 7 knots. YMMV…
 
My previous post said hull speed just under 7 knots. Should read just under 8 knots. My error.
 
Last edited:
6.5-7.0 kts cruise. You can charter one to know if that speed is for you.
 
Where do you intend to use the boat? 110 hp is adequate to move the 36' GB in typical conditions, but if you frequently operate where strong currents or winds are a factor, then a bit more power can come in handy. OTOH, with experience you can get used to maneuvering anything and staying out of trouble. As often discussed when this topic comes up in TF forums, the single six-cylinder will make you happy when you have to spend time in the engine compartment. Twins in a GB 36 make for an overcrowded engine space, IMO.
 
My 30k lb displacenent hull 36 foot Willard has a 75 HP Perkins 4.236. perfect engine. At the time she was built in 1970, a 6-cylinder Perkins 135 hp was an option. Personally, I think that was overpowered vs 75 HP being underpowered.

But it depends on how fast you want to go. My displacement hull wouldn't do 9-kts even if she had a pair of Pratt & Whitney's bolted to her deck.

Peter
 
I like cruising at displacement speed. I have twin Lehman E-Con-O Powers rated at 98/100 HP but using the same block as 120's. I wish I had a single, but cruise at hull speed of 6.5-7 knots at 1350-1450 rpm when bottom is clean, at under 2-3 gph combined.
I recently noticed on my 100 day cruise in Canada and PNW how folks that exceed hull speeds make a huge wake and gotta believe a lot (60-70%) of fuel consumed is to push water instead of propelling the boat with thrust. A round bottomed boat sure feels those long lasting wakes that go for miles, or seem to anyhow.
I did set a new speed record after the Super Moon flood current at the Tacoma Narrows of 12.9 knots at 1450 rpm, but soon paid the price for that speed with tall, steep and fast waves from multiple directions. Much happier going slow on flat water.
 
Agree with the above comments. I have twin 135's in my 36CL. Love them and love the maneuverability, but I would be very happy with a single Lehman 135 and a beast of a bow thruster... Crawling to the port and starboard sides to work on twins is an annual PITA!
Not sure of the diff in the 110, 120 and 135. Anything above 8 1/2 knots your just plowing water....
I think you'd be fine. Take her for a ride...
 
I ran a GB36 up the river system from the Gulf of Mexico to Lake Michigan. I had a single Ford-Lehman 120 HP engine, which is what I am thinking you have in that "110 HP engine." For places where you can expect 1-2 knots tidal currents and if you are happy at 7 knots, this is ok power. However, for steady 4 knots +/- on the nose going up the Mississippi, it is not sufficient IMHO. After that rip I vowed I would not attempt up current river travel in anything that cannot make 12 knots in still water.
 
I agree wholly with Socalrider! We have a GB32 and feel good about one engine. Again, I maintain it to the max and have spare parts. Never leave for far away places knowing there is some little problem somewhere. For power and speed, eight knots is all you need unless you own BP or Shell. I would recommend having a dual primary filter system, like tow Racor 500s at ten microns.
 
JackConnick said:
You'll maybe get 7 knots downhill, probably more like 6.5. Pretty old engine.
I have twin Cummins 210 turbos in mine and cruise comfortably at 8.5 knots at 1600 revs.
Click to expand...
On any comparable boat and depending on the prop size/pitch, a given RPM will give you given speed. You are cruising at 8.5 knots but are using only about 50 HP.
 
rgano said:
I ran a GB36 up the river system from the Gulf of Mexico to Lake Michigan. I had a single Ford-Lehman 120 HP engine, which is what I am thinking you have in that "110 HP engine." For places where you can expect 1-2 knots tidal currents and if you are happy at 7 knots, this is ok power. However, for steady 4 knots +/- on the nose going up the Mississippi, it is not sufficient IMHO. After that rip I vowed I would not attempt up current river travel in anything that cannot make 12 knots in still water.
Click to expand...
My GB36 with twin Lehman 108s (according to Brian at American Diesel) recently ran out to 13.8KT SOG at 2400 RPM. I did a reciprocal course and got about the same, so current wasn't a significant factor. That said I wouldn't want to be running it "on the pins" all the time. I should add that we were moving from one yard to another as part of a refurbishment and she was VERY light.
 
ronobrien said:
My GB36 with twin Lehman 108s (according to Brian at American Diesel) recently ran out to 13.8KT SOG at 2400 RPM. I did a reciprocal course and got about the same, so current wasn't a significant factor. That said I wouldn't want to be running it "on the pins" all the time. I should add that we were moving from one yard to another as part of a refurbishment and she was VERY light.
Click to expand...
Must have been very light indeed. That's a frankly astonishing SOG for not a lot of Mr. Eds in a GB 36.
 
No water tanks. The aft cabin is stripped to the hull so yea, REAL light. My point being that at a given RPM and prop arrangement you will get a given speed. When you are cruising 7-8 KT, hundreds of extra HP is not of any use.
 
I purchase a GB 36 with a 250 hp cummings which the prior owner put in to replace the original lehman 135 hp engine. Per the prior owner the speed went up 2.5 mph
 
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