14hp + mc366

[mrdrh99]

Got to run the boat this morning for about an hour and a half. I had my 10y/o daughter on the front. According to GPS it only ran about 8.5 mph.... Is this right? I was hoping for closer to 15. Now I do need to play with the depth of the motor a bit, it seems to be a bit further down in the water than I thought it would. Also, the hurricane was blowing the chop up so I couldn't spend extended amounts of time at wot.

 

[Sea Rider]

Check with other GPS with at least 1/2 mile run on flat calm no wind waters. 8,5 is extremely poor performance with 14 HP engine.

Happy Boating

 

[mrdrh99]

My prop is pretty beat up.... Anyone have a recommendation on what to replace it with? Maybe something to help performance out?

 

[fbpooler]

For a time, OMC made work motors rated for 14 HP, so there is a chance that is what you have. I do not remember if they had the same lower unit gear ratio, but you should be able to chase down that info.

A beat up prop will definetly influence operation and could wear out the lower unit also. What is your prop identification?

 

[Sea Rider]

My prop is pretty beat up.... Anyone have a recommendation on what to replace it with? Maybe something to help performance out?

That's the first condition you should have specified earlier, that's why you have such a poor water performance. Replace with same new one, with luck should be a medium pitch prop. Wild guessing other props or other prop recommendations can ruin any engine..

Happy Boating

 

[mrdrh99]

I can't find an identification.... Do I need to pull it off?

 

[Sea Rider]

Props usually have pitch numbers cast on prop body, if no number is shown could take it to a prop shop and have it measured, if that's possible will know size and pitch. I like taching new standard factory delivered props and check max wot rpm achieved with current setup, if kaput or in need to change prop to maximize boat/engine combo will know from which number to start.

Happy Boating

 

[mrdrh99]

How much would moving the trim up one spot possibly effect the performance issues such as low speed and not planning? Hydrofoil?

 

[Sea Rider]

For best prop thrust engine must sit at 90° and sib riding parallel to water level once on plane, that's assuming you have a perfect engine/transom height match. If trim is moved will lose best prop thrust, worst if being underpowered. You need a new prop or one in good condition. It's like running cross country with worn soles, Invest on a prop not on hydrofoils. You need to check which diam/pitch prop was factory delivered with, consult engine brand tech department.

Happy Boating

 

[fbpooler]

If your prop is messed up, you are whistling in the dark to expect minor changes to make a real difference. Have you had experience with outboard motors or is this new to you?

Don't mean to be rude, but that info would help us help you.

By all means pull it off and examine it closely.

 

[mrdrh99]

Oh I have absolutely no problem in admitting i'm new to Sib and outboard performance... I'm coming from an intex mariner 4 and Minn kota trolling motor. I'm just guessing off of other threads I've read!

 

[mrdrh99]

No Title

I know it's a crappy picture but that is the prop..... How does that look? Maybe not quite as bad as I thought? But what the hell else could it be? Boat and floor are being inflated well.... 62kp floor 22kp tubes (Saturn recommend 60 and 20)

 

[fbpooler]

Okay friend, being new to these motors just means we have to be more careful with our answers to your questions. We are all constant learners.

The 9.9/15 HP OMC standard motors have through hub exhaust whereas the work motor seems to have the older design motor foot with pin drive. That probably sounds like Greek, but it just means that the motors were generally furnished with low pitch propellers. There are a variety of pitches available for that design which should help your installation realize the power available.

The thru hub exhaust design is a little faster, but the pin drive should give you satisfactory service.

If you look closely at the prop, you should find prop identification stamped in the metal.

You would really benefit by having a tach to check the RPM at speed. Sea Rider would be able to help you find a low cost tach.

 

[Sea Rider]

That prop doesn't look to be in a beaten up state, if with slight upper blade corrosion, could still work satisfactorily, assuming blades are immaculate angled and in top working condition. Being an old model that 14 HP could be rated at the crank, not at the prop, if so, will deliver less HP than it's current 14 HP shown on cowl.

Going for a prop without knowing current factory delivered prop numbers it's a wild guess that could turn into a costly one, unless you happen to have a full bag of props to try them all and check wich one matches best your combo application.

Better yet, sell that oldie and buy a good second hand modern 2 strokes 15 HP engine with exhaust through prop which is more thrust efficient than your current oldie specially if not finding a stamped number on prop from where to go to prop right that engine.

Happy Boating

 

[mrdrh99]

Do you thing bumping the trim up will help performance at all? Going back out Tuesday and planned on trying that?

 

[fbpooler]

That is basically a standard 15 HP motor with the different lower unit. It has more thrust in reverse so worked best for commercial service. (Thru hubs lose their bite in reverse.) 9,10,11, And 12 in pitch props are available to fit it, and it will push a boat nearly or equally as well as the standard 15 HP, so you should find it a good motor. That is a modern design engine, not an old design rated at the power head. Is that boat fit for service with an engine in that horsepower range?

We had an 18 HP with the same lower unit and it pushed our boat faster than the 15 HP thru hub we replaced it with, so don't worry about it not having thru hub exhaust. They come into their own at higher speeds than a motor that size is capable of.

You can play with the transom until the cows come home, but if it is not propped well it will not perform.

Also, a prop can be knocked out of pitch and still look good.

 

[mrdrh99]

Ok... So.... If you were in my position... What would be the first thing you do? BTW.... The boat is actually rated for up to 30hp on the plate.... Boats to go said 9.9 but this isn't moving even close to how the one on their website is Don't get me wrong, I'm not miserable with it but I want it to live up to it's potential

 

[Guest]

Since I been going out on the water I have not seen anything older then Fedor's mid 80's Mariner. Anything older belongs in a museum

 

[Chopperbill]

A tach was mentioned I just ordered this on from Amazon for $27. Got free two day shipping with Prime.

 

[fbpooler]

If I were in your position, I would check out to see if the motor is in good shape, tach it and get an idea of what prop to use, follow the instructions on mounting our man has given you, and use it until you could no longer buy parts . That basic motor was manufactured from about 1972 or 1974 until OMC stopped making the two strokes and have earned quite a reputation as a fishing motor for small boats. The carbs were improved over the years to provide for an excellent trolling speed for a two stroke, and if you look around at boat ramps, you are bound to see many of that series in use today.

I rebuilt a 15 HP on the kitchen table which had melted a piston when the water inlet became plugged with hand tools. They are easy to work on. I also sold our last one a couple of years back which was a 1990 model which we should have kept. We had a 1980 15 HP previously which was stolen. As we used the engines for both fishing and duck hunting, they were run many hours per year. We have nearly a 12 month window for boating here.

We got a 15 HP Yamaha two stroke just before they took them off the market and the performance of the OMC and newer Yammy were nearly identical. The OMC was easier to move around due to its compact cowling and trolled at a slower speed..

Two of my friends still run older models of the 15 HP version and are very happy with them.

People with little experience do not appreciate the motors sold during the 80's and 90's. Once they started using capacitive discharge ignition and got away from sleeve bearings, they changed the face of outboarding. My buddy goes offshore with a 120 HP, 1985 Evinrude quite often. The engine often runs 6 or 9 hours per trip as we often spend the day trolling.