08 merc 60hp efi plane and speed

[shimano19]

I recently bought a 08 mercury 60hp efi 4 stroke and took it out for the first time Sunday. At WOT it takes about 35-45 sec to plane and reaches a max speed of 21mph and 5100rpm. It's on a 16' smokercraft pro angler xl. Prop pitch is 13. Gas is from last season the owner said but stabil was put in the tank. My friend has the same boat and motor and he gets up on plane in 5 seconds and hits 37mph and 6000rpm. What could be the issue with mine?

[irishfield]

Just the rpm tells me you have too much prop on the boat. What prop is on your buddies... see if you can borrow it for a run. Old gas / new gas. Doubt this is your issue, unless you can noticeably see your engine is running rough, but good practice is to always top your tank in the spring with fresh (ethanol free) fuel to give the old stuff a boost.

Edited May 20, 2015 by irishfield

[Bondar]

My 50 hp 4 stroke merc will get my 16'8" lund to 29-1/2 mph at about 5400 rpm and planes fairly quick. My boats about 150lbs lighter than yours. 6000 rpm seems a bit high for your buddys boat but I'm not positive. And your rpm is low. Have you done a compression test on the motor? Any pictures of the engine on the boat?

Edited May 20, 2015 by Bondar

[Sinker]

Yep, something isnt right there for sure.

 

 

My 40 pushes my 16ft starcraft 28-30mph depending on conditions.

 

S.

[shimano19]

The boat is rated for max 75hp, I know something isn't right, I've been told various times it's a prop issue and a handful of people have told me it could be motor related. His boat is at the marina so he's unsure of the pitch. My outboard runs great though. No hesitation and starts first turn everytime

[BillM]

I'm assuming no power trim, where did you set the motor in the trim holes?

[shimano19]

It has power trim, maybe I was to much over trimmed, and they are installed in the second or third hole

Edited May 20, 2015 by past.the.cast.mike

[DRIFTER_016]

Way too much prop by the sounds of things.

WOT on those Mercury 4 strokes should be between 5500-6000 RPM.

Look @ the prop and let us know what the info on it is.

 

According to my guesstimation on the Merc prop selector these would be the best options for your boat.

I would suggest one of the 4 blade aluminium spitfire props. Not expensive and great performance.

 

https://www.mercurymarine.com/en/ca/propellers/selector/#/step-one

 

[shimano19]

I already have a 13 pitch, I would need a smaller one

Edited May 20, 2015 by past.the.cast.mike

[shimano19]

So with the different prop and higher

Rpm is could get my speed up to 30+ mph like my friends

[Sinker]

It should run +/- 30mph no problem.

[shimano19]

I've been getting different answers about prop and motor

[DRIFTER_016]

When I calculated your boat I used 1000# hull weight, 20 gallons of fuel, and 500#'s of people & supplies.

You may need to adjust depending on your particular setup.

[BillM]

Call up Kawartha Prop and ask one of the guys.

[shimano19]

Spoke to one of them already, they said it dosent sound like a prop issue, almost every other place said it does. I want to get it checked out but lots of marinas near me are 2 weeks wait

[irishfield]

Like I said earlier.. take the 5 minutes and borrow your buddies for a test run, if he lives close anyhow.

Edited May 20, 2015 by irishfield

[shimano19]

His boats at a marina 3 hours from me so that's not an option and he's unsure of his prop specs

[craigdritchie]

Mercury says a 2008 60 hp four-stroke should run somewhere between 5,500 and 6,000 rpm at wide-open throttle.

 

If you're tapping out at just 5,100 rpm but the engine seems to run fine otherwise, you're most likely running too much prop. As a general rule, prop pitch alters engine rpm by about 200 rpm per inch. In your case, dropping two inches of prop, that is going from a 13-inch pitch to an 11-inch pitch, should give you another 400 rpm or so, and put you into the correct rpm range at WOT. Dropping one inch further, to a 10-inch prop, would theoretically put you around 5,700 rpm at WOT and likely give you optimal performance. On the Smokercraft, you should be in the 35 mph range running properly trimmed at full throttle.

 

Understand, these are averages and estimates - your mileage will vary somewhat.

 

Many on-water dealerships will allow you to try a prop before you buy it. Go find one, and try a smaller prop. The Mercury Spitfire four-blade comes in sizes from 9.5 to 23 inch pitch. As a four-blade prop, it won't be quite as fast wide open as a comparable three-blade, but it will get you up on plane much faster, and hold the boat on plane at lower speeds, even when it's heavily loaded. That's a fair trade-off for maybe 2 - 2.5 mph at the top end.

Edited May 20, 2015 by Craig_Ritchie

[shimano19]

Awesome thanks for your help ^^ I will be picking up a 11 pitch today, the store told me if i want he'll switch it for even a 10 if I'm not satisfied, thanks!

[DanD]

When you're trying out these props, don't forget to trim the boat out; it'll be different with each prop. My rule of thumb for a fully trimmed boat is, at wide open (on smooth water) keep bringing the bow up, until the boat starts to porpoise and then bring it down just enough for the porpoising to stop. I can usually squeeze out a couple hundred more rpm and 2-4 mph by doing so. You'll know you're getting close to the proper trim; you'll hear some of the load coming off the motor.

I can't find the pic that a friend took, when we were running side by side. I was in my 16' tiller starcraft on plain and trimmed out; only the back 3' of the boat was still in the water, with the rest of the boat level to the horizon.

 

Dan.

[scugpg]

If your hull weight is only 1000lbs and 13 pitch on a 60 I wonder if something else is going on with the engine. Hopefully the prop change fixes things up though but watch those rpms with the 10/11's.

 

That 60 isn't a Bigfoot is it with a different gear ratio?

[Garry2Rs]

Certainly total weight and hull design are factors, but most 16 foot boats with roughly 50 HP should be seeing about 30 mph carrying one or two men.

I once had a glass 16 ft bow-rider that was a birch to get up on plain until I went down an inch on pitch. One inch less gave me a much better hole shot, and didn't really hurt my top speed. If you're only getting 5000 RPM. it might bring you up to 5800-6000 which would be just fine. Some Marinas will let you test a new prop...

Question...Where is the wake?

It should be coming out in the area of the last 1/3 to 1/4 of the hull.

If the motor is trimmed too low, you are pushing the bow into the water and loosing speed.

For the fastest hole shot, trim the motor all the way down, putting the prop under the boat.

As you come up on plain, start raising the motor. You will hear your RPM's increase.

At some point you will hear and feel the prop breaching, or you will start porpoising.

Trim down and fiddle with it to find the sweet spot.

The sweet spot will change depending on wind direction and water conditions.

 

 

[Stef]

Check the height of the motor on the transom. Many so called marinas just drop the motor onto the transom until it rests on the bracket and bolt it up. Properly, the motor should be mounted so that the cavitation plate is at the bottom edge of the stern or so. Most installs mean your bracket is not touching the edge of the motor well but sits 1-2 inches above. If you can fit some fingers under there you're probably good to go, if not lift the motor and re-bolt in some of the other holes...

[Walleye72]

I am wading into a subject that I know very little about but I thought I would at least share my layout for comparison because I think it's similar to yours.

 

I have a Tracker Pro Guide 16 WT with a 2012 Mercury 60 HP 4-stroke. My boat is a fairly stocky, heavy boat for it's length. The max HP is 75. With just me and my normal fishing gear, the boat get's up on plane fairly quickly, (under 10 secs I would think, although I have never timed it), and tops out at approx 30-31 mph at 5800-6000 RPM. Trimming the motor is required to achieve that speed. With another full sized adult, (ie not my 40 lb daughter LOL), time to plane is noticeably longer, probably more like 15 seconds, but again I haven't timed it. I am a new boat owner, and if I forget to trim the motor back down before taking off I notice substantial difficulty and immediately remember to adjust the trim back down. I had hoped the performance would be a little better with two + adults but for a first boat to learn on I'm pretty happy.

 

It would seem that your package is fairly similar to mine. I'm surprised that your time to plane and top speed is so much different than mine given the similar boat style and motor size and prop pitch. I'm wondering if there isn't something else going on to help explain it.

 

Trying the other props might yield useful information, but I would consider other factors as well.

 

Good Luck!

 

Bill

[DRIFTER_016]

I would still like to know what prop the OP has on his boat currently.

Diameter and pitch.