Hey, I'n an old Sailor planning to switch to a midsize (36 - 40 foot) trawler. A friend out in Seattle had a Tollycraft 36 with twin 120 Volvos and told me that in strong currents and tides, he felt a little underpowered. Would a 36 with 1 - 120hp Lehman be a little underpowered in heavy conditions? My homeport is Rockland, Maine.
Adequate power
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Comodave
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Welcome aboard. If you are looking at Volvos there is a thread going on now about them. As to a 36’ with a single 120 being underpowered, there have been a lot of them built that way. You may have to really look at tides and plan your cruise because at times you will almost come to a stop but lots of them out there. We have twin 225 Lehmans and really have way too much power, I derated them to 180 hp by bypassing the aftercoolers. It all depends on how you plan to run the boat and how happy you will be with a 7 knot boat. Personally I would not be happy with that speed, we like about 9 knots but we pay for it with more fuel burn. But fuel turns out to be one of the overall lesser costs with owning a boat. If I were going to cruise 7,000 miles a year then it would be more important to me. But to the average boater the increased fuel cost isn’t that bad.
Ski in NC
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A 36' with single Lehman 120 is considered a good package. That engine is only capable of 8-10kts at full power, but does wonderful at 1/3 power at 7kts. Where it shows its limitations is fighting a very strong current, like can be found in the PNW and some areas of Maine. Time the currents and it will be fine.
To get to planing speed (15-20kts) will take a total of like 400hp. Then engine room is packed and problems compound.
A single 120 in a 36 is just about right.
To get to planing speed (15-20kts) will take a total of like 400hp. Then engine room is packed and problems compound.
A single 120 in a 36 is just about right.
A single 120 would be more than enough to push that boat to hull speed. The question is, do you want to go faster than hull speed? If so, then you want more horsepower and you want bigger tanks, because as you push a boat like that past hull speed the fuel consumption quickly spikes upwards.
OldDan1943
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Sometimes, you have to consider tidal state and current in a cut.
Not a thing wrong with 120hp, single engine if the boat is designed with that engine in mind.
I had a Lugger that would run all day WOT. It was a well maintained engine.
Not a thing wrong with 120hp, single engine if the boat is designed with that engine in mind.
I had a Lugger that would run all day WOT. It was a well maintained engine.
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Scrib
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I own a 36 ft boat with a 135hp Lehman and cruise all over the coast of ME. It is definitely not underpowered. I cruise at 8 kts while top end is about 9.5kts and at cruising speed fuel burn is a little over 2 gal/hr. All said a comfortable and economical cruiser. I'll admit to using auto-pilot on longer jaunts as it can get boring driving for 40 miles @ 8kts!
As far as cruising in ME on an 8kt boat. There are a few places where the current will slow you down but all are manageable either by timing the tide or simply sitting back and enjoying the ride. You're an "old sailor" so I'm assuming you can probably name the places ... Mussel Ridge Channel, Sheepscot River, parts of Pen Bay, to name a few.
As far as cruising in ME on an 8kt boat. There are a few places where the current will slow you down but all are manageable either by timing the tide or simply sitting back and enjoying the ride. You're an "old sailor" so I'm assuming you can probably name the places ... Mussel Ridge Channel, Sheepscot River, parts of Pen Bay, to name a few.
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My Clipper 34 would these days be called a 36', and was over 11 tonne, so much like a current 36' boat in all ways, yet with a Lehman 120hp it was never under-powered..!
Nomad Willy
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NO,
You just take a little longer.
You just take a little longer.
The boat in my avatar is 38' with a 55hp Mitsubishi diesel.
7.2knots in still water at 1800rpm at 0.75gph. $1300 in fuel toronto-bahamas-toronto.
I have to plan the east coast inlets a little more carefully than some but I'll take the trade off.
7.2knots in still water at 1800rpm at 0.75gph. $1300 in fuel toronto-bahamas-toronto.
I have to plan the east coast inlets a little more carefully than some but I'll take the trade off.
firehoser75
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I think it also depends on the boat design (full vs semi-displacement) and the area you operate in. I cannot speak to Maine, but here on the BC coast where we can experience tidal currents of up to 15 knots, there may be times (for example trying to make 2 rapids on the same trip with slack water times only 30 minutes apart and a distance between of 13 miles) that having more power and speed available would be nice. Also, when in heavier weather having more power can be useful.
However, having a 120 hp in a 36 foot boat and utilizing reasonable planning on timing currents, you should find that adequate for hull speed most of the time.
However, having a 120 hp in a 36 foot boat and utilizing reasonable planning on timing currents, you should find that adequate for hull speed most of the time.
FF
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The key is realizing a displacement boat will not go faster , even with loads of HP.
A 7k current can not be bested by having an oversized engine id 7K is the boats top speed.
The most common method of overcoming a foul tide in a displacement hull is anchoring.
Cruise planning is essential to avoid the hassles of foul tides.
Offshore ,wave action may slow passages , no way to climb a fresh 6-10 ft wave and not loose speed , and perhaps have it break on deck.
In a few hours offshore the steep waves get much less dangerous as the distance between them increases and they are less steep.
The most common power level for cruising engines is 3HP per ton (2240lbs) with 5hp per ton at the extreme end of rationality.
A 7k current can not be bested by having an oversized engine id 7K is the boats top speed.
The most common method of overcoming a foul tide in a displacement hull is anchoring.
Cruise planning is essential to avoid the hassles of foul tides.
Offshore ,wave action may slow passages , no way to climb a fresh 6-10 ft wave and not loose speed , and perhaps have it break on deck.
In a few hours offshore the steep waves get much less dangerous as the distance between them increases and they are less steep.
The most common power level for cruising engines is 3HP per ton (2240lbs) with 5hp per ton at the extreme end of rationality.
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OldDan1943
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With a full replacement or semi-displacement hull, having extra HP will help over-come the tidal action and current .... Just more power to press on at the expense of fuel burn.
Ken E.
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Your proposed boat has plenty of power for PNW conditions. Part of boating here is knowing where high-current areas are and transiting them near slack.
Cruising Sea Venture
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I would agree with the other posters here. You would be just fine - maybe better then fine. That would be an excellent package You just have to be aware of your tidal currents, etc., but you should be aware anyway.
We cruised the PNW for many years with our 45’ Puget Trawler with a single Lehman 120 and did great.
We now cruise on our passagemaker - 54’ Cheoy Lee LRT - with twin Lehman 120’s. We run them at 1,500 RPM - which gives us 7.5 knots, 3.15 GPH combined, giving us a 4,300 NM range and our boat weighs in at 90,000 lbs. We just passed 10,000 hours and 70,000 NM’s and the engines are doing great. I’ve never felt underpowered.
Anyway, I think the Lehman’s can handle a lot - unless you want to go fast and/or want you cruising to be focused on where all the fuel docks are located.
Good luck,
Jim and Rosy
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We cruised the PNW for many years with our 45’ Puget Trawler with a single Lehman 120 and did great.
We now cruise on our passagemaker - 54’ Cheoy Lee LRT - with twin Lehman 120’s. We run them at 1,500 RPM - which gives us 7.5 knots, 3.15 GPH combined, giving us a 4,300 NM range and our boat weighs in at 90,000 lbs. We just passed 10,000 hours and 70,000 NM’s and the engines are doing great. I’ve never felt underpowered.
Anyway, I think the Lehman’s can handle a lot - unless you want to go fast and/or want you cruising to be focused on where all the fuel docks are located.
Good luck,
Jim and Rosy
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C lectric
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I too have a 7 1/2 knot boat. I have more power but don't use it. No need to.
You just have to learn about the currents and passes where you travel.
I suspect you had to do that where you used to travel in your sailboat. How much power did your sailboat have and did you ever REALLY need more power? Or did you use your skills and learn about your cruising area.
You just have to learn about the currents and passes where you travel.
I suspect you had to do that where you used to travel in your sailboat. How much power did your sailboat have and did you ever REALLY need more power? Or did you use your skills and learn about your cruising area.
FF
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On the AICW , the East coast N/S highway for boats , most folks can be bothered with the hassle of Tide Tables.
The legs inside between openings to the sea are fairly short , so what is lost in one hour may be gained in the next.
The bridges are a much bigger time looser if you cant slide under without waiting for an opening.
The legs inside between openings to the sea are fairly short , so what is lost in one hour may be gained in the next.
The bridges are a much bigger time looser if you cant slide under without waiting for an opening.
Pete Meisinger
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When the "expert" tells you they feel twin 120s is underpowered you need a better definition of underpowered. I suspect he may be having issues with handling, probably related to small rudders and perhaps no big beefy center keel.
pete
pete
ramkay
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Absolutely not. The 120 Lehman is a workhorse and an unbreakable piece of machinery. You won't be getting more than 5 to 6 knots/hour at around 1800 rpm with a 36 footer but you can be damn sure you gonna get the stable power in any seas. I own a 1978 GB32 with the same engine in and have crossed the English Channel with some pretty high seas 6 to 7 Beaufort scale and some mean tidal coefficient and it performed pretty damn well. Slow but reliable. Keep it well maintained.
Nomad Willy
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“Adequate Power”
Is very close to 10 or 15% above the power to achieve normal high cruise. Usually about 65 to 75% power is where adequate power lives. That way cruise is 45 to 55 % power and max cruise is 55 to sixty percent of power available.
My opinion entirely.
And based on my boat that is adequately powered. 4hp per ton. I achieve hull speed meaning my 40hp is a bit more than needed. Which gives me a bit of extra power .... that I’ve never used. My cruise rpm is 2300, max continuous is 2500 and WOT rpm is 3000.
Most all trawlers are overpowered .. but/and the 4hp per ton is for FD vessels. As one ascends upwards into the SD range power required rises as well. The upper end of the speed range for SD hulls is very close to planing. It actually is at the top end, which is the bottom end of planing speeds.
Is very close to 10 or 15% above the power to achieve normal high cruise. Usually about 65 to 75% power is where adequate power lives. That way cruise is 45 to 55 % power and max cruise is 55 to sixty percent of power available.
My opinion entirely.
And based on my boat that is adequately powered. 4hp per ton. I achieve hull speed meaning my 40hp is a bit more than needed. Which gives me a bit of extra power .... that I’ve never used. My cruise rpm is 2300, max continuous is 2500 and WOT rpm is 3000.
Most all trawlers are overpowered .. but/and the 4hp per ton is for FD vessels. As one ascends upwards into the SD range power required rises as well. The upper end of the speed range for SD hulls is very close to planing. It actually is at the top end, which is the bottom end of planing speeds.
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Marco Flamingo
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That is generally my method, but I will admit it can be difficult. Other displacement boats can leave the anchorage to go fight with a foul current and I stay put, read a book, have a third cup of coffee (decaf). Two hours later, I leave. I can still see them, now 30 minutes ahead of me and having burned twice as much fuel. But I admit that it's hard to sit still sometimes.
Another tactic that I find not quite as frustrating is to travel slow in order to time a passage at slack. Two hours at 4 knots would kill some people, but timing a pass and zipping through without any concerns makes up for it (for me).
I used to think that predicted log races were lame. Having now officially entered geezerhood, I can get quite a kick out of timing things just right, letting my 80 hp Lehman also enjoy the cruise, and using the least amount of fuel. My wife chided me when I was thrilled with a 9 hour and 45 minute cruise averaging 7.6 knots and never over 1,800 rpm. That just doesn't happen by accident with my boat. But it's not for everybody.
Bryant
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I have a GB 36 in Pensacola, Fl. We have very little tide or current most of the time. I have a single FL 120 and I feel that I’m underpowered. One day we were coming in through P’cola pass against the wind and tide and we were only making 3.5kts over the ground. I lived in Whidbey Island, Wa for awhile and I would have had a great deal of trouble with this boat and motor in those waters and conditions and as such would have not been able to use it on many days.
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