Boat slow tonight

[mraz72]

I had myself, another adult and two kids, lake was calm and the temp was in the 60's. Full throttle was 7200 rpms around 33-35 mph, that was it.

Seems really slow, not sure what the deal is.

 

[Gym]

Hi Mike. I'm not very well versed on your boat. I see you're running the 192. Is that a turbo? Does it require high octane or regular fuel? You mentioned 1 other adult and 2 kids. There could be a 400 pound swing here if your adult friend was a football linebacker with his 2 teenage kids. Not trying to be a smart ass but weight does matter.

What rpm and speed range do you normally see? Was this the first time you ran with this type of load as weight does play a key factor in speed. I'll throw out the general causes of slower than normal speed to see if any resonate with you.

Spark plugs, air filter, marine growth or dirty hull, bimini deployed, wind conditions, boat weight & balance (too many sitting in stern area or on one side making it harder to get on plane), high density altitudè (making it harder for the engine to brethe, clean out plug properly seated, no cavitation from impeller (caused by debris in intake, damaged impeller/wear ring or missing sealant) forward/reverse bucket out of adjustment.

I'm sorry to throw out so many possibilities, and there are several more, but not knowing all the conditions and what you normally get for performance makes this kind of a guessing game. Possibly you could give some more info. Your profile doesn't give your location so I'm not sure of your relative altitude. If you are not running with fresh spark plugs & fresh fuel you may want to start there.

 

[4x15mph]

Was your bilge turned on?

 

[haknslash]

Was your drain plug in? Did any water or higher than normal water drain once you loaded up the boat on the trailer?

 

[Speedling]

So rps were down as well which means probably not cavitation.

Weight could be an issue not a huge one.

Forgot to pull anchor?

 

[Cobra Jet Steering LLC]

do you have oil soaking your air cleaner element??

 

[mraz72]

I wet slip the boat, so I don't know about the drain plugs, put them in a month ago and all has been dry.

I can check the air cleaner, I had the boat summarized by the dealer, change plugs and whatever else they do.

One thing I didn't do last year was stabilize the gas, not sure if that could be an issue, but just a thought.

Next time I get in the boat, I am going to go full throttle before the engine gets hot and see what happens. First I'll check the air filter.

Forgot to pull anchor? lol, I have a box anchor and a digger, I would really notice if I forgot to pull anchor, that wasn't the case....

 

[Cobra Jet Steering LLC]

well for sure weak fuel makes the top end drop like a rock

 

[haknslash]

Yup old gas isn't worth its trouble to keep, especially if you filled with ethanol gasoline. Dump the old gas, get some new plugs and I bet she runs good again. Do these boats also have fuel filters? If so might as well get some new ones too.

 

[Zarrella]

Dump the old fuel....change the plugs

 

[Crusher03]

I wet slip the boat, so I don't know about the drain plugs, put them in a month ago and all has been dry.

How long has the boat been in the water? Doesn't take much build up to kill top end speed.

My guess, get a brush and a life jacket, float around and scrub the hull.

 

[swatski]

Yep, dirty hull can easily account for a 20% speed drop.

 

[mraz72]

since I am on my third tank of gas, I am guessing I am ok with the gas. I might be the growth, the boat has been in the water for a month and the water temp is about 75 degrees.

What do you scrub the bottom with?

 

[swatski]

Starbrite hull cleaner
Available at West Marine or bass pro

Followed by your usual routine of car wash detergent then wax.

There is a lot of information if you search, oxalic acid is the active ingredient in Starbright. If you use it a lot @scokill has published his formula

 

[Crusher03]

since I am on my third tank of gas, I am guessing I am ok with the gas. I might be the growth, the boat has been in the water for a month and the water temp is about 75 degrees.

What do you scrub the bottom with?

I just use a nothing special bristle brush from HD, nothing to aggressive.

 

[Julian]

A dirty hull will absolutely cause your boat to go MUCH slower! When I was wet slipping my old boat (before I got a lift), once it got dirty my max speed would drop to 35-37 from 49!!!!!

So if your hull is dirty, don't bother looking for any mechanical issue....clean the hull (out of the water is the best way) and your speed will return.

 

[mraz72]

Next time I am anchroed to a sand bar, I'll take a look. Maybe I'll bring out a brush and get to scrapping....

 

[mraz72]

I guess its the hull. tonight (just me on the boat) I got through the channel and floored it, got it up to 7800 RPMs but only hitting 32-34 MPHs. The engine feels fine, time to plane seems similar. I got gas and felt under the boat, it feels a little slimy but I don't feel anything drastic.

Any chance it is the impeller?

I forgot to pull the cleanout plug, I'll do that this weekend, just to check.

BTW, once heat soak kicked in, I couldn't get above 7200 RPMs, so annoying....

 

[haknslash]

If your RPM's are up but speed slow and the hull doesn't feel or look bad I would look into cavitation next. How is your boat from a hole shot? Does it hook up and go or is there cavitation (lots of RpMs but not a lot of acceleration)? What is the condition of your impellers?

 

[mraz72]

How can I determine the condition of my impellers?

I feel like pickup is fine, just not getting the top end...