Grand Banks 36 single or twin?

Hello fellow mariner!
I am seriously In the market for a 36 Grand Banks. I like many of the advantages of the single engine but need to know the actual differances in fuel consumption. Cruise speed and max speed.
Thank you in advance!

You’ll get a lot of answers and opinions here. Also join, search archives, and inquire on the Grand Banks Owner's Resources forum.

You’ll soon discover that the cost of fuel is one of your least you’ll have during boat ownership. You’ll have to decide whether you want two engines or one based on other criteria and needs/desires. Good luck!

Edit: BTW, welcome to Trawler Forum!

I like twins but in this boat I’d go single because of weight and some other considerations. Singles are hard to find though.

Giggitoni is correct. Forget about fuel consumption differences between a single and twins. It is 5-10% more for the twin: two engines to turn over so more parasitic losses and two rudders and struts so more drag.

You either want a twin or you don't for other reasons than fuel economy.

David

Almost two tons extra weight for the twin. Weight is almost 100% proportional to drag so there may be more than 5-10% more fuel consumption but probably not much more .. 10 - 15%?

You have a formula for displacement vessels that covers weight and drag?

I highly doubt it is anything above a few percent, not arithmetic.

Fuel use is not the decider. There are many threads covering "twins vs single" on TF. Issues include maintenance(incl ease/cost of), redundancy, safety, maneuverability,etc. Our IG is based on the GB36 to a degree, and I like the twins. My previous 34ft Masters was a single, I recently looked seriously at a 2016 Fairway 37(big model change in 2014) with a single, but with thrusters both ends. I`m open minded about it but would likely opt for twins, though if you found a really good boat with a single, don`t rule it out.

I'd try getting to the engine parts between the side of the engine and the hull before deciding on twins in that size boat. Some can be really tough to work on.

Ted

I have twins and a bias for them. But Ted is right, you should take a look downstairs and see what you'll be facing for even routine maintenance with twin engines on this boat. If it has to be a GB 36 for you, a single might just be the ticket.

If GB marketed the 36 w twin 75hp engines or a choice of a single 150hp then I’d go for the twin. No question.

GB widened the 36 somewhere around 1986 and also produced the “Motor Yacht “ version with twins.

Nomad Willy said:

If GB marketed the 36 w twin 75hp engines or a choice of a single 150hp then I’d go for the twin. No question.

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The minimum GB twin here was Lehman 120, Cummins 210, Volvo 165 and up.
My IG beam is about 12ft 6",I had to get down the side of the stbd Lehman to the raw water pump recently, not what I call fun.
Some IG32s( similar to GB32)had twin Lehman 80s, a great combination imo.

Twin or single

In a 36 - I would go a single.

The 36 is not a big boat & IMHO the single's lower initial cost, lower maintenance costs, lower fuel costs, & ease of getting to everything is all a big plus & the Extra room in the Engine room allows you to save usage of four letter words & frustration levels, I do all my own maintenance & love the extra space to do maintenance in comfort, which to me makes it a winner.

You would be happy with the addition of a bow thruster to assist, but on something as small as a 36, it is not mandatory.

Need to learn the single prop handling tricks, but nothing you can't handle.

With twins it is a very tight engine room. As I do all my own work in there, Not fun to do double the amount of maintenance in there with half the room & very tight quarters.

Both work & yes I agree fuel is your lowest cost of owning the boat.

Good luck.

Alfa Mike

A single will have easier access for maintenance. If only one engine, stay on top of maintenance. If you want to go fast to raise fuel consumption drastically, get twins. More likely, the choice will be academic. If you like the boat, buy it whether it is single or twin. Find moving at a knot below hull-speed to be efficient. GBs (single or twin) are over-powered at such a speed.

Have 80-horsepower single and bow thruster, will travel.

BruceK said:

The minimum GB twin here was Lehman 120, Cummins 210, Volvo 165 and up.
My IG beam is about 12ft 6",I had to get down the side of the stbd Lehman to the raw water pump recently, not what I call fun.
Some IG32s( similar to GB32)had twin Lehman 80s, a great combination imo.

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This is essentially what I have in the 34 Californian LRC with twin Perkins 85s. (4.236 inline 4) It's a great combo of efficiency and redundancy with good access all around if one is reasonably fit and agile.

FlyWright said:

This is essentially what I have in the 34 Californian LRC with twin Perkins 85s. (4.236 inline 4) It's a great combo of efficiency and redundancy with good access all around if one is reasonably fit and agile.

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Agile doe not describe me.

I have a Prairie 36 with twin Perkins 6 cylinders and find enough room to perform maintenance, etc. I just installed new oil & transmission lines on both engines and will admit it did require some engine room yoga.

However, I personally prefer having that second engine to get me where I SAFELY need to be over the cost and maintenance savings with a single engine. Maybe it's because I came from the sail boat world and always felt I could use my sails to get home if my engine failed.

If one's rudder and single-propeller are protected by a keel, one can avoid lots of problems. Just ask my two-propeller friends. (If you know me, you know them.)

Captnick2 said:

Hello fellow mariner!
I am seriously In the market for a 36 Grand Banks. I like many of the advantages of the single engine but need to know the actual differances in fuel consumption. Cruise speed and max speed.
Thank you in advance!

Click to expand...

I was considering a 36' as well, its a very efficient hull that tops out at over 15kts on twin 210hp.I joined the Grand banks owners forum to get more info , and there is indeed a lot of very useful inside expertise on lots of diverse subjects.

My conclusion: the teak decks are a deal stopper.

There are literally acres of teak on a GB36'. Each strip of teak is screwed down when it is glued in place, then a wooden plug is glued on top of the screw. After a few years the caulking shrinks and the screws start to loosen and water gets into the plywood sub-deck.

If you strip off the teak, the rotten sub-deck will not support your weight, necessitating a complete deck rebuild......100's of hours work costing $$$

I have always had smaller, outboard and i/o boats and two years ago I went to a 36'twin Diesel ( 40 with bow pulpit and swim platform ) after being unable to find a boat with a single we both liked.
Sometimes it comes down to personel prefference and availability.
Having said I took to docking the bigger boat with the twins almost overnight.
At 7 1/2 to 8 knots I burn about 3 1/2 gallons an hour for both engines.
What I like is the ability to go quicker if I want to get out of weather etc.
So far the only issue has been removing and replacing the port engine fuel pump and that gets done, what every 10 years or more.
In the end no right or wring answer.
Gool Luck,
Bill

Love my twins!

Single vs twin

I am the owner of a Grand Banks 36 with a single 120hp Ford Lehman. I have owned the boat for 20 years and I must admit that I enjoy the extra room to work on the engine. I generally run at 1700 rpm’s with a speed over ground of 7.3 knots using a four bladed prop. We use the boat extensively during the summer months putting on around 300 hours. My fuel burn on average is 1.9gph which includes the diesel heater and generator. One can never argue with redundancy. During our 20 years plus in Southeast Alaska we have been aboard other GB’s of the same size with twins and found the holy place to be very vey tight making maintenance a difficult job.

If single v twins is your only issue, you need to go aboard both kinds. Get down and dirty in the ER of both. Drive both. Dock both. Dock both in a cross wind and in a cross current.
I once helped a friend learn the ins and outs of his ER in a 36 GB with twins. There was lots of room for both of us in the ER at once. Lots of access to everything that was to eventually be serviced. Mind you, neither of us needed to go to weight watchers, but had that been the case, he wouldn't have been able to service a single in the same ER.
The added maneuverability of twins would be enough to convince me, but I recently had a full summer while my mechanic waited for me to return from my boating vacation, in order to repair one of my engines. I lost no time from doing what I love to do, cruising on my boat. If I only had the one, I would have lost a summer. That alone would also be enough to convince me to go with twins.
You will burn more fuel with twins. That is not due to any extra cost of spinning the extra iron, but will be due to your enjoyment of 8 to 8.5 knot cruising instead of 6 to 7 knot cruising. If you still want to go that slow, your fuel consumption will drop to that of the guys with singles. Try both speeds. See which one you like. 8 to 8.5 knots would again be enough to convince me to go with twins.
You mentioned "the advantages of a single over twins". I don't think you have considered the opposite. You owe it to yourself to consider twins. Then you can make your choice and join the camp that you will then be able to properly defend, from true knowledge, not just from religion.

I could give you 600 good reasons not to buy a twin engine boat. Looking for the right single made our search a lot longer than it would have been. It's too long a story why we bought twin screw "Gypsy Star". I still believe every one of those 600 reasons but... I could never go back to single screw. Handling this boat is just too damn much fun.

No specific comment about the GB but before deciding check out engine room access to both sides of the single and twin engines. You may decide better access to the single outweighs other considerations (or you may not!).

Keith wrote;
“If single v twins is your only issue, you need to go aboard both kinds. Get down and dirty in the ER of both. Drive both. Dock both. Dock both in a cross wind and in a cross current.”

One may learn something about the GB by running into headwind w a steep 2 or 3’ chop. There may not be much difference but the heavier twin may take a lot more water on the wheelhouse windows. I wonder if anyone has some apples to apples experience to apply to this question.

markpierce said:

If one's rudder and single-propeller are protected by a keel, one can avoid lots of problems. Just ask my two-propeller friends. (If you know me, you know them.)

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^^ What he said

LOVE my single fully protected prop on my tug!

...and before you say it; yes i know i'm due for bottom paint

Like my Single

I purchased a '77 Grand Banks 36 with a single John Deere. I liked the idea of less maintenance but was afraid of reduced maneuverability. As a few others have commented - I cannot imagine how hard it would be to work on anything in the engine compartment with twins. I've already replaced bilge pumps and fresh water pumps.

We did the big jump across the gulf moving the boat from Ft Myers, FL to Gulf Shore, AL. 56 hours and nary a hiccup from the engine.

I use just under 2 gal/hr at a cruising speed of 1700 RPM. This gives me 7-9 knots depending on currents and wind. Top RPM is 2100 and delivers about 10 knots.

I've learned to dock OK, but I am very aware of wind speed, direction and current. I feel comfortable that I will get better with more practice.

I've had twins in most boats I've owned in 60 years. Mostly singles in commercial boats. I like the back up, but have only returned on one engine twice in those 60 years. But they have always been heavy duty diesels. Not yacht duty. I have never damaged a prop on twins. Twins don't take twice as much fuel as a single unless you're running flat out in a sport fisher. Twins allow a faster cruising speed in a displacement hull. I burn 8.5 g/h @ 10kts in an 80 ton, 83' boat. And that's not the most economical speed, but I like it. I've never felt I needed a bow thruster and can dock anywhere there is 83'. I have even backed into an opposite slip in order to enter a slip where the passage between slips was 60'. Even in marinas with multiple 90° turns. Twins make handling so much easier.

Based on personal observation, twins are at least as maneuverable as a single with bow thruster. Personally, with a single engine and a bow thruster, I don't feel handicapped.