Engine choice on Grand Banks 42

GB is a semi-displacement hull and will plane with enough horsepower. The theoretical top-speed is infinite.

The difference is fuel burn. If it took 45 litres to get somewhere in 3 hours or 45 litres to get to the same place in one hour (sadly, its not linear) its the same thing...

The best GB42 I have seen had a single 6 cal Gardner that idled at 400 rpm and came with a drum of Brasso.

T210DRVR said:

So far I’m seeing 7.5 to 7.7 knots at 1500 RPM with Lehman 120’s. I can get a bit over 8 knots at 1800 RPM but the engines seem happiest at 1500.

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My 56,000 lb DeFever 44 with Lehman 120s goes about 7 knots at 1,600 RPM. Lasy year doing the Loop, we consumed 3.5 gallons per hour for all conditions, including generator time. That equates to 2 nautical MPH which I think is pretty good for a heavier boat.

I have Cat 3116 straight 6s in my 1993 GB42. I typically cruise at about 1800/2000 RPM, 70-80% rated RPM at about 10K speed. Get about 1.2 NMPG at that speed. I don’t work on the engines (only let Cat mechanics turn those wrenches) other than oil changes but I do all the other support/systems repair & maintenance with room. It’s tight sometimes, but I’m not a small guy either!!

I looked at boats with all different engines, happy with my choice as it provides good economy and engine room space. Oh, and you can’t beat the sound of a CAT engine!!!

dz,
What’s the power and displacement of the Cat 3116’s?

I don’t have the spec sheets with me (boats is in storage in Wisconsin) but if I recall, the displacement is 6.6L and 305 HP. If needed, I can pdf you the spec sheets (including fuel burn chart) when I’m visiting the boat next week. Just let me know....

dz1drwww said:

Oh, and you can’t beat the sound of a CAT engine!!!

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I read somewhere that CAT engines are somewhat noisy. Is that what you're suggesting?

No, not at all.... I’m my opinion they sound like an engine should sound.

John R M said:

I read somewhere that CAT engines are somewhat noisy. Is that what you're suggesting?

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Nicknamed "Clatterpillars"! but I've personally not found them to be that loud.

We have the twin Lehman 135's in our 42' CHB Present Sundeck - semi-displacement. At 1800 rpm we cruise at 8.7-9.0 mph and burn about 3.5-4 gal per hour. Love those engines - as has been stated they are very easy to work on and they run fairly cool at 175 degrees consistently (especially after I installed two new water pumps). But I did pull a bone-head issue a few weeks ago on the TN River - checked the strainer on the starboard engine, and then promptly forgot to re-open the sea-cock - burned up a brand new impeller But again, pretty easy to repair.

Those Lehman’s are proven marine engines and easy to work on. In addition they have a very favorable footprint!!!!

Here is another engine I have come across; British Leyland 165HP, not a turbo. Anybody out there with a pair of those? I wonder how easy it is to get parts?

I looked at a 36 with a Leyland. I couldn’t find a source for parts. Too bad as it was a nice boat.

dz1drwww said:

I don’t have the spec sheets with me (boats is in storage in Wisconsin) but if I recall, the displacement is 6.6L and 305 HP. If needed, I can pdf you the spec sheets (including fuel burn chart) when I’m visiting the boat next week. Just let me know....

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Thanks much dz.

Pat T said:

Here is another engine I have come across; British Leyland 165HP, not a turbo. Anybody out there with a pair of those? I wonder how easy it is to get parts?

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I had a GB with a British Leyland. It was a 200 hp turbo. Same engine as the 165 but with an intercooler. Removed the intercooler so I had a 165. Engine was bulletproof. Not a single hiccup in 15 years of ownership. American Diesel has the parts. Talk to Brian Smith at American Diesel for any info you could possibly want.

Like dz1, I have a GB 42 Classic (1994) with 3116 Cats. They are rated around 300 hp in this configuration (a small turbo). When looking to buy a boat (I was only interested in GB 42's), I saw boats with up to 475hp twins - which I thought was ridiculous - 300 hp engines were the most I wanted in a trawler that I intended to cruise at about hull speed. If I wanted to cruise at 20 kts or more, I would have bought a Sea Ray and I would't be on Trawler Forum.

We cruise at about 1600 - 1700 rpm and even there, I worry about underloading the engines. I bring them up to 2000 occasionally to "burn the carbon out." Can't imagine what damage would be done to 450-475 engines if you ran at hull speed most of the time. Contrarily, I'm not interested in the 20 - 40 gph fuel burn you'd need to run those big engines at a proper speed.

I think I've hit a sweet spot on my boat. We burn about 4-5 gph overall (including gen and the two engines) and everything seems to run happily. I'm happy to have the capability to run at 13 kts if I have too (due to weather or other trouble) but glad I don't have to do that all the time in order to keep the engines healthy.

Very glad to have the inline 6's instead of v-8's for accessibility in the engine room.

Xsbank said:

GB is a semi-displacement hull and will plane with enough horsepower. The theoretical top-speed is infinite.

The difference is fuel burn. If it took 45 litres to get somewhere in 3 hours or 45 litres to get to the same place in one hour (sadly, its not linear) its the same thing...

The best GB42 I have seen had a single 6 cal Gardner that idled at 400 rpm and came with a drum of Brasso.

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I'm late to the discussion here, but if memory serves and the 42 Xsbank saw with a Gardner was a motoryacht, then i believe it was a boat that Tony Fleming built for himself while he was with American Marine.

I guess the point of my post was that the Gardner at 120 hp is adequate for the 42 GB. A single Lehman 120 was an option back in the ‘70”s for the 42

Dawdler said:

I guess the point of my post was that the Gardner at 120 hp is adequate for the 42 GB. A single Lehman 120 was an option back in the ‘70”s for the 42

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single Lehman 120 would be a nice package in the GB,lots of room to work around it and efficient.

Specifically what power plant choice would be found in a 1980-90 Classic 49'?

Doodleasc said:

Specifically what power plant choice would be found in a 1980-90 Classic 49'?

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Most likely twin Ford Lehman 120's. If repowered, then likely Ford Lehman 135's or Cummins 6BTA's or maybe a John Deere

slowgoesit said:

Most likely twin Ford Lehman 120's. If repowered, then likely Ford Lehman 135's or Cummins 6BTA's or maybe a John Deere

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Towards the 1990 end of the range they might also have Cat 3208s. The one GB49 MY locally is an early 90s build with twin 3208TAs.

I believe they came with whatever the original owner / dealer specified. However most if not all that I have seen of that vintage and size were 3208 TA’s.