Outboard advice

Charlie Jones s/v Tehani · Feb 21, 2015

I used a Yamaha 4 HP 4 stroke on a 21 foot boat. Absolutely loved it. Once you get used to the quietness and fuel economy of a 4 stroke, you'll be sold.

And i push 7500 pounds of boat at hull speed with an 8 HP running at half throttle

keys please · Feb 21, 2015

A good two stroke has a lot of power and not as much weight as the newer four strokes… much easier to move around…. Just my opinion….. if I see a two stroke omc 9.9 or 15 that is clean from lake country….. I will likely buy it…. I have used them on dingies and dive boats forever….

Ron20324 · Feb 21, 2015

Slogfish said:
...How fast can you stop the boat then back up with 4hp or 8hp. Backing into a slip in a crosswind and current is what I'm wanting to accomplish. Does a 4-stroke have more low end torque than a 2-stroke would have?

+1
Mostly, the prop on a 4-stroke has more area then a 2. The extra area helps alot.

Ted · Feb 21, 2015

You'll be fine with an outboard with 6-8 hp unless you are dealing with currents that are really strong. I've used a 7.5 hp on a 25 foot boat that displaced 3700 pounds with no problems other than it going under water occasionally in big following seas. I've used both 2 and 4 stroke engines and prefer the 2 strokes. They were smoother running and had more power for a given rated horsepower. They do not idle as smoothly as 4 strokes. It's no big deal to mix oil with gas and the benefit is you never have dirty oil circulating through your engine which helps them last a long time. Two stroke engines are also lighter which keeps weight out of the end of your boat which will help performance a bit. If you are concerned about the environment, the 4 strokes run cleaner and generally cost more to purchase but are more fuel efficient.

Bob 04 H260 · Feb 22, 2015

With a lot of motors they use the same form factor for the 4 to 6 hp motors and then a bigger size for the 8, 10, and 15 hp models. Having a two cylinder engine is a plus if you can find one, idles better, quieter. I have a 4 hp Evinrude 2 stroke that has 2 cylinders runs very nice.
The correct prop will make a big difference in how well a motor will push, stop and control your boat. If you can have a link to connect the motor to the tiller it makes a huge difference in a Marina.
Johnson made some excellent long shaft sailboat motors sold as Sailmaster, 2 strokes, with correct gearing, prop and charging coil.

Good luck, Bob

Crazy Dave Condon · Feb 22, 2015

Slogfish;

If you are at Belews outside of Greensboro and considering the coast of North Carolina, I use to own American Marine & Sail Supply out of Zebulon just east of Raleigh with offices at times at the coast and Lake Norman. Also I was a Tohatsu dealer and concur with you on the 3.5 as it stunk without the reverse. Therefore I will speak from knowledge and experience.

Depending on where you go, you will need an engine with a reverse and there you will experience currents in some areas for example on the ICW near Beaufort, around New Bern, rivers, etc... In addition most tidal currents are wind driven in the Pamilco and Albermarle versus tidal which many do not comprehend. For the 21, I would recommend a 5 or 6 hp engine.

The two stroke engines which used an oil mix in the gas but are no longer being built due to EPA laws that took affect in 2006. Therefore, most new small engines are four stroke. There are many but Tohatsu also builds the Nissan and small Mercury engines as well. If you are lucky enough to find straight gas, then bite the bullet and purchase that. If not and you end up buying the ethanol or corn crap as I call it, you will need to purchase the additive for the gas to combat the ethanol. With that, always run the gas out of the carb or motor as I would say when leaving the boat; otherwise it will gum up the jets in the carb and then you will have to clean the carb out.

If you need any further information, feel free to contact me thru the forum. I did move out of North Carolina to Virginia last year returning home.

gettinthere · Feb 22, 2015

The 2 stroke will be much easier to service. With ethanol, that has become likely for small outboards.

Add an external fuel/water separator to the fuel line to help minimize the problem.

HukilauMike · Feb 22, 2015

Not just an outboard issue

If you switch from a two stroke to a four stroke, you may need to also change out the transom support bracket. Most of the OEM support brackets were made to support two stroke engines and are not rated to hold four strokes. It's not just the weight, it's also the torque generated. I'm not an engineer and can't opine on whether a two stroke bracket that is rated to hold a 70 lb. two stroke engine can safely accommodate a 50 lb. four stroke. but that is the question. When I replaced my outboard about 8 years ago, I specifically bought a new two stroke so I didn't have to make that decision. Now, you can't buy a new small two stroke. Good luck.

Brian S · Feb 22, 2015

I'm going to beat my usual drum: don't overpower. Simply get a high thrust prop. Lowering pitch, increasing blade area, and changing shape from speed prop to elephant ears makes a world of difference, and improves stopping and reverse. Small 4 stroke engines generally have a very small idle jet. Keep that clean by avoiding ethanol and using marine Sta-bil and Seafoam. www.pure-gas.org

uncledom · Feb 22, 2015

I went propane on my dink and my buddy did the same on his Catalina 27'. Not the same size of course but the Lehr is a nice little motor that has no fuel issues such as go along with today's gas. Propane is pretty easy to find, easy to carry, and is multipurpose as we use the same tank to power the Magma grill. You need to make sure you stow it so it can not "spill" below decks as it is heavier than air and volatile. I like that it's one less fuel to have aboard.

Charlie Jones s/v Tehani · Feb 22, 2015

Brian S said:
I'm going to beat my usual drum: don't overpower. Simply get a high thrust prop. Lowering pitch, increasing blade area, and changing shape from speed prop to elephant ears makes a world of difference, and improves stopping and reverse. Small 4 stroke engines generally have a very small idle jet. Keep that clean by avoiding ethanol and using marine Sta-bil and Seafoam. www.pure-gas.org

Good luck avoiding ethanol! I've got a 120 mile round trip to get it. However, many marinas DO carry it. I swear by SeaFoam and StaBil though Use them always.

Crazy Dave Condon · Feb 23, 2015

Whether two or four stroke, at the end of the day, let the fuel run out of the carb.

futuristictech · Feb 23, 2015

I learn a lot with this topic. Thank you!

Charlie Jones s/v Tehani · Feb 23, 2015

Crazy Dave Condon said:
Whether two or four stroke, at the end of the day, let the fuel run out of the carb.

Or if like me you keep the boat in the water, run the engine once a week at least. Although the SeaFoam does help a lot, movimg fresh fuel through helps too.

futuristictech · Feb 23, 2015

related to what you write, I got questions that starts a new topic related to the speed weight and HP. Please read
http://forums.sbo.sailboatowners.com/showthread.php?p=1188395#post1188395

Gobsmacked · Feb 23, 2015

Outboard

Since new two-strokes are no longer sold in this country, any that you buy will be used. That means you could be buying someone else's headache that he wants to get rid of.
Weight is also a major consideration on the transom of a 21-foot boat. Your boat should move well with a 4-6-horse four-stroke, some of which weigh about 60 pounds. That's a reasonable weight to carry to and from the boat and to mount on the outboard bracket while you are hanging over the stern.
Four-strokes are quieter than two strokes, but the difference is far less noticeable in the smaller engines (under 10 HP). The same holds true for fuel economy.
I'd also recommend that you Google some reviews of the various brands. Suzuki, Yamaha and Honda get the best reviews, while Mercury gets the worst. Interestingly, Tohatsu, which also gets decent reviews, makes the small Mercury outboards, but the dealer where I recently bought my Suzuki said the Mercury uses a slightly different design that has a lot of problems (he recommended the Suzuki over a more expensive Mercury that he also sells.)
Whatever you buy, follow the advice of previous posters who recommend closing the fuel valve and running the gas out of the carburetor after each sailing trip.

CharlzO · Feb 23, 2015

If you do end up two-stroke, and would like a little help to try to find ethanol-free, here's a handy link.

http://pure-gas.org/

I've found that a lot of places around me do sell ethanol free, though usually only the premium level. I find it a cheap enough price to pay for the e-free stuff though. It's not like I'm filling a 50 gallon drum of it.