Outboard Motor Question

[Sam Buschell III]

Hello,

I have sailed my 7.9 with an 8hp Long Shaft Mercury 2 stroke for the last 20 years. It came with the boat.
It pushes the boat at just over 6 knots in most conditions.
It was stolen this fall and I'm investigating replacement options.

Does anyone have experience running a long shaft (20 inch) 6hp Mercury 4 stroke?
I'm inclined to buy Mercury for service and part availability reasons in the Great Lakes Region.
What boat speed are you capable of sustaining.
Any issues with strong current, head winds, etc...?
Do you run the prop is came with or something more like the Tohatsu Sail Pro four blade prop.

Thank you,
Sam

[cklamp]

I'm not sure brand matters as much as it used to. The mercury outboards in that class are made by Tohatsu to my knowledge. I have a 3.5 Nissan on a 21' sailboat, and it'll accept Tohatsu and Mercury parts. Has a mercury Cowl on it right now:) I am pretty sure the same holds for the 4-6hp motors as well, not sure once you move up into the 8-10 range though.

My 7.9 also came with what is likely the original motor. It's a Mercury 5hp from 1985, so it's close in date\make\model to my 7.9. I haven't used it much though, but will eventually try to move up to a 6hp as it won't incur any extra weight penalty. From what I understand it's really just a different carb, and i've seen 4hp merc\tohatsus that have installed the bigger carb for more power. The reduced weight came in handy when I broke the shear pin off when I was out with my brother. We just took it off the mount, and pulled it up into the cockpit to replace. Not going to happen a lot, but it was still handy.

Current motor pushes pretty well, but I did get the higher thrust prop off ebay... If I were cruising where I was going to deal with stronger currents I might go with an 8hp class motor, but I haven't done much of that yet, so haven't felt the need.

That being said, I sail in the PNW, not the great lakes... but, food for thought for ya.

Later
C

[Sam Buschell III]

Thank you C.

What speed does the 5hp push your boat?

Sam

[cklamp]

I've only had it out a few times, and the sensor wasn't working. Have received a warranty replacement from Airmar, but haven't been out yet. will let you know if I ever do and know it's working correctly:)

Later
C

[AJ Oliver]

I have that motor on my own 7.9 and yes Tohatsu and Mercury are the same.

It has run quite well for over ten years, and my motor repair guy says they are reliable.

But I did get the EXTRA long shaft, and think it is a better choice, very few cavitation issues with prop coming out of the water.

I keep it simple with rope start and no cockpit controls (but I do have long arms!)

Hmm, they may not make the extra long shaft anymore.

Looks like around $ 1,800 for a new one.

[AJ Oliver]

My 6hp will easily do 5.5 kts at around half throttle.

[Sam Buschell III]

Thank you.

[Stef]

I had 2 stroke 7.5 hp Mercury. It came with the boat. Everytime I used it, a small oil slick formed. Started to lose power, probably compression.
So I purchased a Tohatsu 6 hp sail pro with high thrust prop and extra long shaft several years ago. I steer with the tiller, just throttle at motor. It's been a great motor. Comes with and alternator to charge your battery.
I never really run full throttle, usually 3/4. Boat goes about 5.5 knots at 3/4 throttle.
I purchased it online and it was delivered by UPS.

[Sam Buschell III]

Thank you Stef.

[SailingUphill]

My hull number 68 was a 7.5 HP Evinrude, and it pushed the boat to hull speed at 3/4 speed on flat calm water.

Present hull has a Nissan 4 stroke (2010 model) 6HP long shaft. Boat hits hull speed at about 7/8 throttle. That last 1/8 just makes more noise. Haven't had any issues with headwind up to 35 knots, WOT into 35 knots boat does about 5.2 knots. We're on an inland lake so not much chop with that.

I think 6hp is a pretty good compromise size.

Some observations. 4 stroke outboards are significantly heavier than their same horsepower 2 stroke counterparts. New outboards under 20hp are all mostly the same company made. Don't buy a Merc, a Tohatsu is the same motor for 10-15% cheaper. Want something "different" buy a Yamaha or Honda. I personally think the Tohatsu motors are quite good, and worth the money.

There are nice propane alternatives, just expect less power and more fuel consumption (but no carb issues). I think Merc is making propane outboards, and I think they are a worthy option. Gotta be honest though, a nice 3.5 gallon fuel tank is hard to beat even with a fiberglass tank of propane.

[Whiteaad]

I upgraded from a Johnson 8 2-stroke to a Mercury 9.9 4-stroke extra long shaft. Overall I have been very happy with the upgrade. Significantly quieter engine and I am able to cruise 6-6.5 at about 3/4 throttle with high thrust prop. I can easily push through any headwind/conditions without issue and with no cavitation. The reason I chose Merc over Tohatsu is because shifting is controlled by twisting the end of the motor tiller which makes navigating in port more convenient. The 4-stroke 9.9 is significantly heaver so the type of sailing you do and weight distribution throughout the hull is something you need to consider. We only do PHRF racing in our yacht club and still perform very well to the S2 7.9 rating.

-Aaron
"Sweven" Hull #235

[Sam Buschell III]

I thought I would share my experience with the 6hp Mercury 4 stoke long shaft outboard from this summer.
Boat speed is 5.5 to 6 knots full throttle.
Fuel consumption is about 0.55 gallons per hour.
Motor easily pushed the boat up the St. Clair river this year with about 2 knots of head current.
I think it is a pretty good option for the boat.

Sam