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-   -   dinghy outboard: Honda 2.0HP vs Mercury 3.5HP (http://www.sailnet.com/forums/gear-maintenance/48037-dinghy-outboard-honda-2-0hp-vs-mercury-3-5hp.html)

sqyntz 10-15-2008 07:50 PM

dinghy outboard: Honda 2.0HP vs Mercury 3.5HP
 
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

tommays 10-15-2008 07:54 PM

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

sailingdog 10-15-2008 09:51 PM

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.

Sapperwhite 10-15-2008 09:54 PM

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.

poopdeckpappy 10-16-2008 12:02 AM

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'

chef2sail 10-16-2008 12:37 AM

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

jgeissinger 10-16-2008 01:10 AM

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.

scupper42 10-16-2008 01:11 AM

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.

Valiente 10-16-2008 01:14 AM

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.

jjns 10-19-2008 12:47 AM

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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