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Outboard Engines Limit

4K views 24 replies 18 participants last post by  wolfy 
#1 ·
I am looking at a boat with a fairly new Outboard engine (about a 100 hours) 9.9 four stroke.

Assuming there are no technical issues with it. Are these engines able to run continuously for 70nm, as a motorcycle or a car would, or are this motors limited to short runs?

Any information is welcomed
 
#5 ·
Fantastic. Thank you very much for the information. This gives us a much wider search area to look for a boat.

I have to rely on the engine to bring us home in case we are not confident enough to do the first trip to our moorage fully on sail.

I'll make sure is well serviced before the first trip.
 
#7 ·
I am not sure recommend a 70 mile delivery for a shakedown cruise, especially if you don't know how to sail. If you can't split the delivery into two days or bring along a skilled sailor, you might want to consider hiring a Captain or renting a trailer.
 
#10 ·
Same with oil. Make sure you carry some to top off.

On a new-to-you engine, you probably should take the time to learn its habits...

Run 1 hour, check too see if oil consumption is noticeable. (Probably not.)

Run 5 hours, check oil.

Run 10 hours, check.

As others have said, if you're running 50% power (well, 25%-75%) it ought to go non stop virtually forever. (Yes, you probably should stop every 100 hours to change the oil, or whatever your mfr recommends.)

If you idle too much, you may gunk up the plugs but new 4 strokes seem to have fewer problems with that than old 2 stroke engines did. On the other hand small 4 strokes sip so little fuel (carb jets are so small) that they are sensitive to old or contaminated fuel, and varnish deposits.
 
#11 ·
Sounds like a reasonable plan. Keep in mind as people suggest running it the motor at 50-75%. My guess is a boat running a 9HP outboard would be doing 5 knots or less unless the conditions are very favorable. Even 30-40 miles a day can be a long stretch at that pace, plan for daylight and weather.
 
#13 ·
Had a small cape dory with an outboard in a well. In any kind of sea water would rise in the well above air intake and engine would stop. Couldn’t restart it until dried out.
Would suggest OP look carefully if bailout points are available to him and how far away they are. This is more important than the total length of the trip. Would suggest he examine if the bailout points would require anchoring, picking up moorings or entering slips. Ideally if his engine quits he can sail into a harbor and anchor until he sorts himself out.
Would suggest he attend to his anchoring equipment as well as the engine and have a good VHF in case he gets in to difficulties. He needs to be prepared for the possibility of no engine and no wind requiring a tow or assistance.
 
#14 ·
Given the issues with OBs on sailboats that have already been mentioned, the OP would be well advised to have towing insurance (like TowBoat Us, SeaTow, or part of boat policy).

While the newer 4 strokes are more fuel efficient, until the parameters of the new (to the purchaser) OB are understood, it would be prudent to figure on 1 gal of gas per hour for a 9.9 at full throttle and then allow at least a 100% margin for safety. So, assuming 5 mph speed in flat water (no wind or tide) and 75% throttle, the whole trip would take 18 hrs (straight shot—no detours) and consume 13.5 gal of gas. With a 100%margin, the OP should have at least five 6 gal containers of gas available (along with OB oil if a 2 stroke). If the weather turns nasty or there is a foul tide, the amount of fuel would be greater.

In any case, the OP would be well served to have bail out options planned ahead of the trip.
 
#16 ·
Wow, thank you so much for all the excellent advice guys.

We would never be more than 6 miles from land at the widest crossing and we will tow a dinghy behind us. We also plan to enroll with the towing service if the trip happens.

We have all the electronics as well, but no precaution is ever enough on unfamiliar waters with a new boat.

Thank you also for the fuel calculations, the rate of gas consumption is new to me.
 
#17 ·
It's very difficult to pour gasoline from a 5 gal jug into an outboard motor or into a 3 gal. gas tank. When the boat is dead in the water, it rolls sharply with the waves, and you spill a lot of fuel over the cockpit floor and sometimes yourself. My remedy was to buy 3 portable fuel tanks, and fit each of them with a quick connector. When one runs out, I just disconnect the hose and re-connect it to a full tank and we're under way again in a minute.
 
#18 ·
Our prior boat was a Niagara 26 with a 10 hp four stroke OB. 25" leg. Mounted on a factory transom cut out, and the prop never over-reved due to pitching in a decade. Trick is to have a boat actually designed from the git-go for an OB. Most boats are not -- you can tell by the bracket mounted on their transom.

We once transited the WA coast and were under way for 46 hours continuous. We used several fuel tanks, and just plugged in a full one when the motor died.... there was no wind to help us on that particular weekend. Burn rate was a half gallon per hour @ 6 kts.

We used a hand cranked fuel transfer pump, but nowadays everyone uses a "rattle syphon". No spillage that way.

Our first engine was a Honda 10, and then we moved up to a Yamaha Hi-thrust 10 (3 to 1 gear ratio).

Happy motoring, and sailing!
 
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#19 ·
I ran my used Honda 9.9Four from Put-on-Bay to Leamington, CA at full throttle in a 7.6 Colombia without fail, it was about a 25 mi. trip. I'm pretty sure I would need to stop for gas to go 70 mi. It was 100 degrees out and no wind and I felt very confident that little motor could have gone to Buffalo if I asked it. Keep oil in it and you should be fine.
 
#20 · (Edited)
Just providing my fuel consumption data for perspective:

C&C 24 with 4hp 4-stroke Tohatsu. I maintain 4kn at 30% throttle. Fuel consumption rate is almost immeasurably small.....say 4-5hrs/gallon (conservative) in fairly calm conditions, waves less than 3ft.

I have a 6 gallon tank and wouldn't hesitate to go the 70NM in a pinch.

Definitely watch the oil levels though; they are harder on oil than I would have imagined for such small engines.
 
#21 ·
Well OK, the OP's question has been answered, engines can do this, yes.

I'll also just point out it will be impossible, even if attempted on the Summer Solstice, to make the trip without either exiting or entering an unfamiliar harbor in pitch darkness. To say neither is a good idea would be an understatement.

Me, I would plan on making this a three day trip, both to de-stress it and allow for weather.
 
#22 ·
If your boat likes to "hobbyhorse" in a head sea, you might find your outboard not getting enough water to drink or to "drive" when the bow dips and stern rises. Cavitation, overspeeding, and overheating are the result.

The one place you need reliable power in rough weather is if you're trying to claw your way off a lee shore, and can't do it under sail alone.

If you aren't in that kind of geography, then good. I've found outboards to be reliable and wonderful in light air and sea conditions, all day and all night. But I respect their limitations compared to a fixed prop way beneath the waterline, and in front of a nice big rudder.
 
#23 ·
IMO 2 strokes will out perform and provide greater reliability than the complex engined 4 stroke, they are also substantially lighter....due to less parts being used during construction.
Over the years (40+) having used 15, 25, 70, 90 and 115hp 2 strokes on my various Tenders I have NEVER had one breakdown or even foul a plug.
I guess if you're a maintenance guy like me you'll make sure she's looked after....i.e. Lower unit gear oil, spare lower unit seal set,
spare plugs and plug wrench just in case, correct mix of 2 stroke oil with fresh mid grade fuel.
Sounds as if the OP should dump the sail boat and purchase a nice little cabin cruiser.
 
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