# dinghy outboard: Honda 2.0HP vs Mercury 3.5HP



## sqyntz

I am trying to decide between the Honda BF2D 2.0HP 4-stroke outboard, and the Mercury 3.5M 4-stroke outboard. Following is a summary of my digging. If anyone would like to add opinion, fact, rants, or anything else please do so.

The outboard is for a Mercury 340 inflatable with air deck, LOA 11'2", empty weight 92 lbs, capacity 1500 lbs. I will be the first to tell you that both of these outboards are somewhat underpowered, but all I am trying to do is get from the boat to shore and back without rowing. I am willing to sacrifice the HP of a larger outboard, for portability, ease of handling, an integral fuel tank, and lower cost.

Honda BF2D 2.0HP:
-pros
--excellent portability (27 lbs dry weight) 
--excellent reliability (honda brand)
--air cooled (avoid problems from silt when operating near shore)
--longer & better warranty

Mercury 3.5M
-pros
--slightly more HP than Honda
--good portability (38 lbs dry weight)
--slightly larger fuel tank: 1.5 qt. (Merc) vs. 1 qt. (Honda)

Both (Honda & Mercury):
-pros
--integral fuel tank
--360 degree steering
--3 star emissions

The Honda has a centrifugal clutch, which disengages the prop at idle speeds, while the Mercury has a transmission (Forward+Neutral). I don't see a clear advantage of the Honda's clutch over the Mercury's shifter. Maybe there are fewer moving parts in the Honda's clutch, but one disadvantage of the Honda is an inability to rev the engine in neutral. With the Mercury, I assume the engine can be throttled up in neutral. If anyone owns a Honda BF2D and can clarify, please do.

I really like the Honda brand, and recognize that they have a reputation for well engineered stuff.

I haven't been able to figure out where these are manufactured, but that is also a factor in my decision.

I don't really have good numbers for fuel efficiency (note to manufacturers: please provide GPH for various throttle/RPM settings). I guess the smaller displacement of the Honda makes up for the slightly smaller fuel tank. The Honda spec sheet states that the Honda will run for 55 min. on a tank of gas at full throttle, so I could estimate .25 GPH or less at 75 percent throttle.

Here are the specs from the respective web sites:

Mercury M3.5 FourStroke Specifications:
HP @ Prop...................3.5
kW @ Prop...................2.6
Max RPM (WOT)...............5000-6000
Cylinder/Configuration......1
Displacement (CID/cc).......5.2/85
Bore & Stroke (in)..........2.16 x 1.42
Bore & Stroke (mm)..........55 x 36
Cooling System..............Water-cooled w/thermostat
Ignition System.............CDI w/electric spark advance
Starting....................Manual
Gear Ratio..................2.15:1
Gear Shift..................F-N
Steering....................Tiller with 360° turning
Trim Positions..............4
Exhaust System..............Above prop
Lubrication System..........Splash
Recommended Oil.............Mercury 4-Stroke Outboard Oil
Oil Capacity................300 mL / 10 oz
Fuel Induction System.......2-valve single overhead cam
Integral Fuel Tank (Gal)....0.3
Integral Fuel Tank (L)......0.95
Shaft Length (inches).......15/20
Shaft Length (mm)...........381/508
Dry Weight (lbs.)...........38
Dry Weight (kg.)............17
Available Propellers........Standard equipment
Warranty....................3 years
CARB Star Rating............3

Honda BF2D Specifications:
Type..............................4-stroke OHV Single Cylinder
Displacement...................57cc (3.4 cubic inches)
Bore & Stroke...................45 x 36 MM (1.80 x 1.40 inches)
Full Throttle RPM Range.....5000-6000 RPM
HP Rating @ Propshaft.......2HP @ 5500 RPM
Induction Scavenging........OHV
Valves per Cylinder............2
Fuel Delivery....................Single Venturi
Ignition System.................Transistor Pointless
Starting System................Manual
Lubrication.......................Wet Sump
Cooling System.................Forced Air
Trim Range.......................4-Stage 5°-10°-15°-20°
Tilt Range........................75°
Gear Ratio........................2.11:1
Propeller...........................3 Blade Polypropylene 7 1/4 x 7 1/2 inches
Recommended Transom Height....(S) 381 mm/15 inches
Dry Weight....................(S) 12 kg - 27 lbs.
Warranty.......................5 years


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## tommays

The 2 HP is just to small the 3.5 is almost 80% more power


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## sailingdog

The 2 HP also has no transmission. That means trying to use it to maneuver at very slow speeds is very difficult, since the centrifugal clutch tends to cut in and out at low speeds. Neither has reverse. 

Personally, I don't think that the air-cooled 2 HP is a good idea. I have the Tohatsu 3.5 HP and it is a very solid little outboard. Tohatsu makes many of the Nissan and Mercury models as well, including the 3.5 HP you're looking at.


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## Sapperwhite

EDIT: dog beat me to it, but.....

Just a heads up; Tohatsu makes Tohatsu, Nissan, and Mercury (small Merc, under 10 HP) outboards. The only difference is the sticker. You can save yourself a couple hundred by getting a Tohatsu 3.5.

I bought a 3.5 from these guys:

Tohatsu Outboard Motor 3.5hp 4-Stroke

I'm happy with the outboard after a full seasons use. I use it on a 9 foot Achilles with HP inflatable floor. I have to use a tiller extension and drive from well forward in the boat to get it on plane. You probably won't get on plane with either choice. I got mine from Onlineoutboards.com for $850 no tax.

I am in no way affiliated with OnlineOutboards.com other than being a satisfied customer.


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## poopdeckpappy

I think the Honda is too small, I had the option of a Honda 2hp & the Nissan 3.5, I went with the 3.5 on a 9'6" rollup dink and that's cut'n it kinda thin

Ya might even consider stepping up to 4-5hp for a 11'


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## chef2sail

I got the 4 hp Tahatsu from outboards online for 950. The advantage is that it has both integral tank as well as external connection too. .37 galllons wasnt enough for the wife and I as we like to explore the rivers and creeks her on the Chesapeake when we anchor.

Dave


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## jgeissinger

*Honda 2*

Have you ever heard a Honda 2 horse outboard actually running? They remind me of an old "cruise 'n carry". They are the noisiest damn outboards on the planet. In my collection of old outboards I have a British Seagull that is quieter than a Honda 2. Honda builds a lot of great stuff, but not this one. Get the Mercury.


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## scupper42

*The Honda is Light*

I have the air cooled Honda. It won't push our little Walker Bay up on a plane, but that's not why we bought it. It's still way faster than rowing...

It is quiet. It is light. We can sling it with relative ease from the dinghy to the stern rail, but barely - I wouldn't want a heavier engine.

Don't be talked into to more power if it is light weight you are looking for.


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## Valiente

I _have _the Honda 2 HP, and you can get a different clutch...still no neutral, but a proper throttle arm.

2 HP is indeed light for a 11 foot inflatable, but I took a different tack and got two tenders, a 55 lb. 10 foot Portabote and an 88 lb. 10 foot nesting dinghy that tracks a lot better than an inflatable or even a RIB.

I got it because, like you, I'm not in a hurry. I have found, however, that it will push me, my wife and my kid at five knots. I have found that it will push me into 15-20 knots on the nose and two-three foot waves at three point five knots. The integral tank's range at full power in such conditions is about 50 minutes. Yeah, I've been testing it!

My wife can "one arm it" out of the forepeak, where it is clamped to a piece of wood through-bolted to the workbench. As my wife is quite compact, if fearless (she sailed with Alex under his vast cruising spi!), my rationale might not be yours, but I found the light weight, the mechanical simplicity and the air cooled aspect won me over the slight extra "oomph" of 1.5 extra HP but 60% extra weight, plus the need to flush the salt out.

It's a very parsimonious engine. A single one-gallon jug is good for four fill-ups, and gives you about 3.5 hours run time at full throttle. So that's about 17.5 NM/gallon.

It sounds like an angry bag of bees. I like it. It does the same thing every Honda I've owned does: you have to pull once with full choke on cooler days, then put the choke to half, and give her a single yank. They start every time.


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## jjns

We had the 2HP Honda (in the days before the cent. clutch) bought it for the lightweight aspect. I could live with it's short comings until the 1st cold start on choke. Instant take-off. (newer clutch models may be more forgiving?). 
Got back from our trip and traded it up to a 2.5HP Yamaha (37lbs). Neutral was worth every penny and every pound.
Also, it is quiet and will run for a good hour on 1L of gas at full throttle.
It is not a fast combination (4-5 knots w/2 adults) on a 9.5 Zodiac Cadet (90lbs), but it is sufficient.


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## 121Guy

*Honda 2HP*

We too have the 2HP Honda short shaft with centrifugal clutch. Have used it for four seasons with no problems whatsoever. Use it to push a 12 foot air floor inflatable. It does not allow the dinghy to plane but that was not our goal. It will push the dinghy with 4 people around for a couple of hours at half throttle without worrying about fuel. It uses a great amount more at close to full throttle. Here are some things we think Honda should consider to make it a better product. It is very loud at anything more than idle. It does not offer a remote gas tank hookup option. It does not offer any options on improving the plastic prop.

One thing not mentioned on the plus side is that as a Honda, it should run forever with good care. It has to be the easiest engine I ever worked on for oil change, gear lube change and overall maintenance. Also, it claims to be the cleanest running (lowest polluting) gasoline engine made.

If I had it to do over again I would strongly consider the next largest Honda. I think, but am not certain, that at the time it was a 5 HP and was roughly $200 more. It had reverse and a remote tank....but was heavier and consumed quite a bit more fuel.

Good luck with your choice.

121 Guy


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## Valiente

It's nice to see measured advice here full of real-world information. The Honda, being at one end of the weight/convenience spectrum, has design aspects "not for everyone", and yet not everyone uses their tender the same way.

The "leaping into forward" thing on the neutral-less Honda concerned me...until I actually tried it! You can grip a dock or simply loop a line to defeat it, but me, I just aim the boat and let 'er rip!

The other aspect of this, of course, is that I don't see the Honda as a small outboard so much as a "big, tireless rower": I frequently will row away from the boat first to see if there's wind or traffic nearby that needs to see me..._then _I will fire up the Honda and be on my way.

I have done the 180 degree flip thing and gone dead astern and I would say this works marginally better than "reverse" on a standard outboard. I have also simply done slow circles to stay "on station" if I am fiddling with a radio or something.

Anyway, the ease of use and portability trump this model's "little ways", but I can see that if you left the engine on the dinghy on occasion, or if you were regularly pushing 4 people or half a dozen diesel jugs, a more beefy, more standard small outboard would be a better choice.

This suits us at the moment, but that could change. An air-cooled 3.5 HP at 35 lbs. would be near perfect, for instance.


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## dohenyboy

in the same situation as you, I have gone with an electric trolling motor. much cheaper, even with buying a small agm battery.


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## sailingdog

The real problem with this is that you have a very limited run time... and what do you think will happen if your battery dies in a harbor with stronger currents? Hope you packed the oars.  BTW, if you do run the battery down below the 50% point too often, it will die very, very quickly.

With a gasoline powered dinghy outboard, you can just re-fuel the engine, and you'll have a good long run time. With the Tohatsu 3.5 HP, the 1/3 of a gallon gives you about 1 hour of run time or so. With 2.5 Gallon jerry can of gasoline aboard, you've got over eight hours of run time, assuming the outboard's tank was full to start with.



dohenyboy said:


> in the same situation as you, I have gone with an electric trolling motor. much cheaper, even with buying a small agm battery.


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## billangiep

Another consideration for those looking for small outboards is the Suzuki 2.5. http://www.sailnet.com/forums/gear-maintenance/46579-2-5-suzuki.html

*DF2.5 Specifications*


Model Name: DF2.5SHorse Power: 2.5Shaft: 15Displacement: 4.15 cu. in. (68 cc)Weight: 29Cylinders: 1Ignition: Suzuki PEIBore X Stroke: 1.89 x 1.50 in. (48 x 38 mm)RPM Range: 5250-5750Maximum RPM: 5750Starter: MStart w/Man. ChokeOil Tank Capacity: .32 qt. (.3 lit.)

Fuel: UnleadedGear Ratio: 2.15:1Standard Propeller: 3 X 7 1/2 X 5 1/2Steering: Tiller


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## Valiente

sailingdog said:


> With 2.5 Gallon jerry can of gasoline aboard, you've got over eight hours of run time, assuming the outboard's tank was full to start with.


Yes, this negated for me the need for a separate fuel tank. If I am 45 minutes of full throttle away from the shore at anchor in hairy conditions, (think three NM away!) I wouldn't use the tender in the first place: I would bring the boat inshore and temp anchor or seek a wharf.

I have confirmed in the open lake in rolly conditions that I have closer to an hour of run time on my Honda 2 with the one-litre integral tank, but I'm assuming 45 minutes full out for a safety factor.

Refilling isn't an issue even in those conditions (I've done it with Zodiacs during jug-to-tank refills on long runs), and a one-gallon jug is laughably small compared to the sort of jugs I carry for the "mothership"....but that one gallon gives me THREE HOURS or 15 NM in flat water of range, with two refills along the way.


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## JIO

I purchased the Honda 2hp this summer for my Mercury 310 airdeck. I went for this model due to the light weight of the motor. I have been pleased with the selection and with my wife and 2 young kids in tow, it moves along at a reasonable speed.


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## tonybinTX

I've the Honda 2hp on an 8ft zodiac air floor. Again - no planing. I use it to troll a line around the inlets and when we go out for a night or two on the lake to get our German Shepherd to the bank.

There is a mod to convert it to a tank system.

I don't have an issue with starting. Just be sure to be sitting down when you yank on the starter and you'll do fine.


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## MajorMischief

We too purchased the Honda 2HP with centrifugal clutch a few years ago... not for a dingy but as the auxiliary for our Precision-18. The major advantages are: low weight and simple maintenance (since it does not have a water pump). The major disadvantages are: difficult to operate at very low speeds since the clutch disengages and the necessity to top up the fuel tank before heading in (so you don't run out of gas in a busy harbor). With a displacement hull, our boat would not have been any happier with a more powerful engine. The Honda 2HP powers the Precision-18 close to hull speed!


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## jamesbence

We have both the honda 2.3 and the merc 3.5... there are pro's and cons with each 
the honda will just about plane the dinghy with a 10 stone guy in it (me) performance wise the merc is far better at getting the dinghy on the plane and much more solidly built... I have found both engines perfectly reliable
A downside with the honda is that the recoil start is very snatchy and the clutch is the same but it is more portable and air cooled which makes it a bit noisy but with obvious maintainance benefits. I also have a sealine s 21 which broke down and beleive it or not the merc pushed me to the safety of the harbour with no issues I would pic the merc any day despite the fact its a little heavier but both are excellent portable engines


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## MajorMischief

The biggest problem with an outboard these days is making sure it has new clean fuel. Our gasoline is now treated with 10% alcohol, and this dramatically shortens the shelf life. One nice thing about the Honda is that I can turn it upside down and drain the tank when I'm not going to use it, and there is a screw to drain the carburetor. 

I also add Sea Foam to all my marine fuel to help clean the carb jet and preserve the fuel. Ditto for the lawn mower and snow blower. The government is talking about bumping the alcohol up to 20%. This will certainly wreak havoc with small engines, and will also void the warranty on new ones.


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