boat slow to come on plane

[jcritt1]

20' Chapparal, 305 mercruiser, 21 pitch stainless prop. when giving it throttle the boat just rides there with the nose in air for quite awhile, eventually the nose comes down and it planes out. It doesn't seem to matter with 3 people or just me. Doesn't really bother me since I troll 99% of the time , but it just seems to me it should plane out quicker. Would changing the pitch of the prop help? If anybody has any ideas any input would be greatly appreciated.

[jason]

check you points and see if they're gap correctly....thats the problem i had this yr...

[Gill-T]

Carb problem, water in the gas ......lots of reasons.

[Has Been]

How long you owned the Boat? Any problems before this? Last time it was tuned up ? 21 pitch on a boat that size seems a little steep. My 21' 305 has a 15" pitch. I switched from a 17 pitch ,which was about the limit I thought.

[fishkiller16]

go to a 19 pitch prop to start, when you drop in pitch you gain rpms higher rpms = better holeshot- better holeshot = faster planeing. if 19 still doesnt help go to a 17. after you get it figured out go to a stainless it will plane better due to less flex.

[jcritt1]

Thanks guys, I've had the boat about 4 years,runs great (knock on wood) seems to have plenty of power and doesn't bog down at all just doesn't seem to want to get moving. I guess it has always been like this although primarily trolling and just putting to where I start trolling it has never really bothered me too bad. Although now my kids are getting old enough to ski and tube and it would be nice to get them up easier. I will try the pitch change and see if it helps. Thanks again

[Trap Jaw]

We had the same problem with our old 4Winns. It was the prop. I'm not sure how you have your boat set up, but with ours we had too much crap on the back. Between cooler, kicker and just misc gear there was too much weight to let the motor wind up. Found out that that set up was fine for an unloaded boat, but throw all that and 3 people in and the only way we could plane out was for everyone to move to the windshield. Another thing to consider is the age of your motor. 21 pitch may have been fine when it was new, but engines loose power over time.

[ray koziatek]

1 deg = 200rpm , the best way is to have HP and total weight ya wanna move ,call a prop shop and they will recomend proper pitch.....with 120hp and a 17 pitch we all gathered at the front too droped to 15 in and with 4 guys it gets on plane ok and reaches max rpm in calm water 26mph, so if yer rpm guage is right and yer 400 rpm under max drop 2deg ....6 to 800 rpm and go with 17 deg .....proper pitch will lessen the load on entire drive system and improve gas millage....................take a standard transmission car and try to start out in third gear see how long you need to get up to speed specally on a slight hill (extra guys in boat)

[L&M]

1 deg = 200rpm , the best way is to have HP and total weight ya wanna move ,call a prop shop and they will recomend proper pitch.....with 120hp and a 17 pitch we all gathered at the front too droped to 15 in and with 4 guys it gets on plane ok and reaches max rpm in calm water 26mph, so if yer rpm guage is right and yer 400 rpm under max drop 2deg ....6 to 800 rpm and go with 17 deg .....proper pitch will lessen the load on entire drive system and improve gas millage....................take a standard transmission car and try to start out in third gear see how long you need to get up to speed specally on a slight hill (extra guys in boat)

Glad to see I could finally teach you something ya remembered.

[ray koziatek]

lucky guess... Thanks Hank....

[rshubuck]

It does not hurt to ask but. Some of these prop shops will let you borrow a few props to try. Prop selection is a very hard thing to get right. There is some other factors to be aware of. Each brand prop may be different from the other. Some props are cuped. Diameter plays a big role also.

If you stick to the same brand prop and design you should have no problem going to a less pitch prop.

[ Post made via iPhone ]

[keithg]

if you have trim tabs they can also help.start out all the way up and after you are are around 1800-2000 rpms give em a brief shot or two down.should raise the back.had an underpowered bayliner once only way to get on plane.try the pitch first

[K Gonefishin]

I agree 21P is alot of wheel I would try a 17 or 19. I'm actually having trouble spinning my 21P with a full load right now but only with a full load, with 2 people it's fine add a 3rd and 4th and it's boggy, higher temps and humity with warmer water play a role per my dealer. I only have the problem in July-August, weird.

[Tim Bromund]

Is this a new problem or has it always been that way? If it is new,first you need to identify why it changed.

After having my boat rebuilt in 2003 (floor, stringers, motor bunks and transom) it picked up at least 500 or so pounds from all the new wood, epoxy, fiberglass etc that went into the reconstruction (plus the 200 lbs of sand bags I now have in the bow as ballast because the boat was decidedly transom heavy after the rebuild) and all of a sudden, I couldn't get anywhere close to the recommended rpm range at WOT. It is a 5.0L 230 HP Merc Alpha 1 in a 1986 24' Thompson Hardtop. It was really lugging the engine and I was getting maybe 3600 rpm at WOT (4200-4600 recommended at WOT).

It had a 14.5"x17 pitch quicksilver 3 blade alum prop which at the start of last season I replaced with a Mercury Black Max 16"x13 pitch alum 3 blade and that 4 degree pitch change and 1/2" extra diameter made all the difference in the world. That 25 year old boat runs like new, jumps up onto plane and tops out at around 4000-4100 rpms, so I still could have gone 1 more deg of pitch down (they also make a 16x12).

Adding trim tabs will also help a bunch if the boat doesn't already have them.

Tim