plane at 4000 RPM

[dgizzim]

I have a 2005 3100SE with trim tabs, two 5.0 MPI, and two Bravo 3 outdrives. Why does my boat plane at 4000? The dealer put the props on. Do I have the wrong ones?

[Franco_2100SC]

You should be able to get up on plane without assistance of tabs.. Although its gonna take umph to get the bow over the initial wave. I just have a small 2100SC but with tabs fully withdrawn and engine trim all the way in the I go full throttle and the boat rises up over this wave its pushing. Initially, the engine struggles to increase the rpm from 2500 to 2700 but as it starts to rise out of the water, from 28 to 2900 the engine starts to unwind and I pull the throttle back to 3000. At this point I push the outdrive out a bit til its just above the double hash mark indicating full in, I then us the tabs in a very short burst to get the back to rise up a tic more and the bow slicing through the waves. At this point the rpm that was tac'ing along at 3000 rpm without any throttle adjustment increases to 3200 and the boat speec is around 38mph.

Now I detailed all this on my boat to give you an idea, but I'm guessing that your boat should not be all that far off.

KKKKFL

[seapuppy]

you need to find out what props you have...it sounds like you might be overpropped but here's the rip...what is your wot...wide open throttle rpm's...you should be between 4400-4800 rpm max...but check your owners manual cuz the mpi engines will actually rev to the rev limiter...I have the 6.2ltr engine with a b3 drive....they tell me that redline is 5280 rpms....so...what props do I have??..they gave me 20" pitched props...I plane fine..but I cruise at 4200 rpm....plane at about 3500 rpms......it's hi..but that's what they say I need.......

[MaxumNewbie]

2300SC, 5.0 220HP, I also plane at about 3200-3400 rpm. I also cruise at about 4200. I dont think I have tabs.

[pilotpak]

I have a 2005 3100SE with trim tabs, two 5.0 MPI, and two Bravo
3 outdrives

dgizzim...I notice an inverted Smile in your post. I'm about to buy a new 3100SE with 5ltr Mercs & BIII drives. Are you unhappy with this drive combo ? Do you think that the boat is under-powered ?

I am concerned, because I test drove a "new" (Dealers Demonstrator) Larson 310 at the week-end and the boat was unable to plane with 2 average people on board. The larson also had 2 x 5ltr Merc's with BIII drives. The engines sounded OK, so I'm guessing that we could not plane due to a very dirty hull.


Wayne
Bayliner 285

[seapuppy]

PP...when you tested the larson...was it in the water for quite sometime??..the b3 drive is pretty awesome and with the 5ltr..it should plane up pretty easily...but...was the engines 2bbl carbs or 4bbls??..or even mpi's....what yr is the larson...??...if the hull is dirty, there is no way it will plane.....
I have a 28ft maxum with a 6.2ltr b3 and it does quite well in it's planning......

[pilotpak]

Seapuppy,..it's being sold as a new boat, dealer has been using it as a demo - about 11 hours I think from memory. I'm told it's been in the water (saltwater) for six months, but my guess is probably about nine months.

The engines are MerCruiser 5.0 L MPI BIII (260hp each) so the thing should fly.

I did notice lots of growth on the hull, but I did not inspect the sterndrive.....I suspect there's maybe high phosphate or nitrates in our local waterways here, as one of the fenders on my 285 was left floating in the water for just 2 weeks and it grew barnacles and hair algae about half an inch in length.

Wayne.

[seapuppy]

then that's the problem...if you have any growth on the hull...it's going to be a real slug...have them pull the boat, power wash it and then try the seatrails....when we ran ours for the first time ..this thing just jumped up and road like a dream...... :?