OMC issue while turning

ETC_Val

Cadet
Joined
Sep 23, 2007
Messages
11
First of all thank you for any response to this post. Last weekend I was out with a full load of 6 people in my 1985 19.5' Bayliner with a chevy 305 and OMC 800 outdrive. Two questions to follow:
1. During a turn, fairly sharp one I experienced what seemed like prop slip( motor reved higher, but lost speed). This also happened again when taking off to plane out after long <5mph cruise( had 5 of 6 people in very back of boat). Wondering if this is a weight distrabution issue, prop replace issue, or something in outdrive giving way?

2.During this same trip I experienced a very difficult time planning out with the group of six people(not the slip issue just not enough power to plane out). This was easily fixed by moving 2 people up to the cabin doors. Wondering if both issues are prop related and is downsizing prop would give me more holeshot as topend is just fine.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: OMC issue while turning

Moving to Prop Topics and questions.
 

JUSTINTIME

Captain
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Sep 2, 2006
Messages
3,284
Re: OMC issue while turning

are u always have 6 people ?
what is max weight for the boat
 

Dhadley

Supreme Mariner
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Feb 4, 2001
Messages
16,978
Re: OMC issue while turning

What prop do you have and what is the top rpm with an average load?
 

ETC_Val

Cadet
Joined
Sep 23, 2007
Messages
11
Re: OMC issue while turning

Currently has a 14 1/4 x 19 omc prop. Top RPM's not know havent had boat out since tach was fixed, but im pretty sure it can get to optimum rpm at wot. Problem isnt wot rpm as much as with a heavy load in rear and while truning fairly hard I believe im experiencing prop slip. Just wondering if that is normal due to load, things are fine with only four people onboard, just the struggle of planning out and prop slip when all are in the back.
 

MikDee

Banned
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Jun 6, 2007
Messages
4,745
Re: OMC issue while turning

6 people is quite a load for that boat, & motor combo. Is the prop slipping, or is it just having a hard time planing under those conditions? (because the latter would be normal).
 

Boomyal

Supreme Mariner
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Aug 16, 2003
Messages
12,072
Re: OMC issue while turning

without a tach any guessing is pointless. However I have two suggestions. Get Smart Tabs, with that 305 and 6 people, you'd be up on plane in a blink of an eye. I also believe that they will help keep the prop biting in a hard turn. It did on my lighter 20 ft'r.

Also I'd send your prop out (if it turns out to be the right one for your boat) and have the blades cupped.
 

QC

Supreme Mariner
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Mar 22, 2005
Messages
22,783
Re: OMC issue while turning

Sounds to me like blow out . . . If it revs up only under certain circumstances, that's blow out. Some hulls blow out with some props, testing a few others can help. Also feathering the throttle can help in those turn situations. If the prop is good for everything else. learn to drive around the blow out. If not start shopping . . . ;)

Also sounds like she is over pitched for a big load and or trimmed too high. Or you are down on power. Do you have Select-trim (OMC Powertrim)?

Edit: What Boomer said too ^^^^^
 

MikDee

Banned
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Jun 6, 2007
Messages
4,745
Re: OMC issue while turning

IMO blow out can be caused by a prop that is too small in diameter versus pitch. Different manufacturers have different diameters versus pitch ratio's, But if you don't run this load all the time, it doesn't pay to get a larger diam prop (15"X19") or bigger diameter. As Boomyal stated, Smart tabs would probably help you out either way.
 

Boomyal

Supreme Mariner
Joined
Aug 16, 2003
Messages
12,072
Re: OMC issue while turning

.... larger diam prop (15"X19") or bigger diameter. As Boomyal stated, Smart tabs would probably help you out either way.

My 800/302 came with a 15 x 17. Sounds to me like you would do well with one of these, but cupped.
 

ETC_Val

Cadet
Joined
Sep 23, 2007
Messages
11
Re: OMC issue while turning

Hey thanks for all the help guys. Tach is fixed took her out yesterday hitting 4800-5k at wot, had plenty of power throughout, but was just me onboard. Gonna reprop next weekend(good deals atm on boating items). I believe that I am experiencing blowout because feathering the throttle fixes the issue. Any advice for new prop though bout 14 1/4 x 17 for better holeshot when loaded down(top end not very important to me). Any thoughts?
 

1730V

Chief Petty Officer
Joined
Feb 14, 2004
Messages
563
Re: OMC issue while turning

Yup, BLOWOUT. You do not want to go any lower on prop pitch. I would not run that 305 any past 4800.
 

ETC_Val

Cadet
Joined
Sep 23, 2007
Messages
11
Re: OMC issue while turning

Yeah I know the wot rmp is at the high end atm, but I never run at wot, only time has been to measure the rmp's at wot. Just started looking at smart tabs never heard of them before, nifty little things, anyone have any personnel experience with them good or bad? I may just have to grab a set if they are all that they are cracked up to be.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: OMC issue while turning

Smart Tabs are easy to install and they work well. I personally like helm adjustable tabs better, but they are more $ and a much tougher install. Smart Tabs are very simple and do what they say.

I would try some cup on what you have prop wise. That should solve the blow out, but you will lose a little hole shot. Four blade can be better too.
 

180shabah

Rear Admiral
Joined
Mar 26, 2005
Messages
4,995
Re: OMC issue while turning

Do a search on this site for smart tabs, you'll find all the praise you need:D
 
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