justfishing

I would never try to compare the speedo to GPS. GPS will be consistent can't say the same for a speedo.

To me it doesn't make any sense to leave a proformance boat in the water. As much as you think it is clean it is probably dirty than you think.

What is growing on you hull is growing in your cooling system. Cool engines run better and last longer.

Stray current!!! Stray current causes electrolysis. Guys running battery chargers. Cruiser with shore power etc.

h20guy

Hi as I said in a previous post I have had a handheld gps unit on my boat on multiple occasions and have compared the GPS reading to my speedo readings and my speedo was dead on every time. As for my boat being in a slip in the water for approx. 5 months I spoke with Shockwave before doing this and they said that the boat should be fine as I do take it out of the water about once per month to clean it and let it be out of the water for a little while. Having it in a slip I get to use it a whole lot more than I would if I had to trailer it every time and it's kind of a large boat to be trailering around all of the time anyway. I wish my marina (No electric at any slips) would allow me to have a lift but they don't so it is what it is. My boating season is pretty short here in Michigan and I like to use my boat as much as possible. The 496 Mags have a closed water cooling system and only use the lake water for the exhausts. My Exhaust system has both internal and external flappers in it and it' a high enough rise that leaving it in the water isn't a problem. I'm on an inland lake in a nice bay so it's fairly calm water the majority of the time. I will double check the speed with my GPS and verify the RPMs again as I may have been trimming the boat up a bit more recently to try to get the same speed that I had a couple of weeks ago. The bilge is very dry and so it doesn't appear that any water is coming in from the few transom fittings that are on it. Just the Drive, Tabs, and Exhaust pipe outlets.

ph1971

iTrader: (1)

GLENAMY 242SS

iTrader: (1)

What would you do with it on a 6 day cruse?

SB

iTrader: (1)

Is 3 nights and 2 days okay ?

BUP

iTrader: (9)

I think he met tied up not moving for days on end. But will add the comments after this --- one has to laugh.

If its a mechanical issue engine side - possible crank sensor. is always a guess. Have the engine scanned and see if it shows 100 percent available power ??? the 375 hp 496 max rpm stock OEM is 4800 I understand it has some raylar parts on it -- so what is the rpm range of the engine currently ?

ph1971

iTrader: (1)

RSCHAP1

With RPM same and same prop/pitch, only thing could be slippage.
Prop hubs have always seemed good or bad to me.
I have never actually seen one slip a little and then fix itself.
Only other place I can imagine slippage is coupler.
There isn't black rubber dust and shavings in the bilge is there??
With everything else presented can't see what else could be causing a 4 mph loss.
Being water logged, heavier, and more slip of prop in water...?
If actually same RPMs, same prop, and really 4 mph slower; only seems like a very few things can cause such a thing.

Sydwayz

iTrader: (1)

They make solar powered lifts.

Or a EU2000i Honda Generator to roll down the dock in a wagon wouldn't be that big of a deal. They make cheaper knock offs too, and the only significant difference is noise.

h20guy

So a couple of comments here, first off the propeller is totally fine I have a depth sounder on my boat and I know the lake very well. When coming into the Sandbar I put the boat in neutral once I'm in 4' of water and start trimming up the drive and coast into my mooring spot. When I leave the sandbar I push the boat out into chest deep water before boarding it and then fire up the engine and wait until I'm in at least 6' of water before getting on plane. I bought this boat used but I baby it as much as possible it has a full mooring cover on it when I'm not using it which has 2 Vico Marine boat III style vents in the cover so there is air flowing in and out of the boat. As I said my marina doesn't allow any lifts at all (if they did my boat would be on one) and there is no electric power at any of the boat slips it's a pretty rustic smaller marina (addressing the comment about people using battery chargers on their boats). Plus the boat slips aren't super wide mine is about 9.5" wide. I had the computer (PCM 555) updated by Whipple (their corrected version of the HO program) when I did the camshaft upgrade the new rev limit on it is now at 5400 RPM, as the Cam's power range is 1400 -5200 rpm. So think of my engine as a 496 mag HO+ , as it has a better cam than the HO engines do and is producing some where around 450 -460 HP. I was hoping someone would comment about the fuel pressure being set at 50 PSI and saying dang that sounds very rich as my thoughts are it may be too rich especially now that the weather is warmer here and that could be causing the loss of speed? Will the Mercury scan tool detect if the engine fuel mixture is too rich? I haven't pulled out any of the spark plugs to see what they look like as of yet. As I said in my original post the engine sounds and runs fine and that cam sure makes it sound meaner and cool. For the last post comment about seeing any black fragments or shavings in the bilge area, no everything in the bilge looks normal and it's very dry in there.