10' GWInvader with 70 h.p. Merc Help

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GWInvader

Cadet
Joined
Mar 29, 2003
Messages
11
This boat was built in the 60's and rated at 50hp, so i thought a 70 couldn't hurt. i bought the motor from a guy who races boats and this motor is actually not much bigger than a 50 horse. The boat does about 50 or 55 mph. Thought it should be a lot faster than that. i'll be getting a tach. this spring, so i dont' know what it's running at right now. i'm running a 10in. dia. prop with a 13 in. pitch. I'm thinking i can go to a larger pitch, but dont' know how much trouble i'll have planing then. Does anyone have any ideas????? Thanks
 
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steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: 10' GWInvader with 70 h.p. Merc Help

Im no expert but with that size motor you probably need at least a 17 inch prop.<br />You may be badly overreving now.I wouldnt run wot without a tach.Also at 70 hp you are running at almost 50% over the rating.Possibly against the law and surely leaving you open to legal troubles if anyone gets hurt. Be real careful.
 
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Hooty

Rear Admiral
Joined
Oct 2, 2001
Messages
4,496
Re: 10' GWInvader with 70 h.p. Merc Help

Your thinking is right. You'll need a tach for sure a perferably some sort of speed indicator. I was in Basspro last week and they had a Garmin GPS Unit on sale for $99.95.<br /><br />c/6<br /><br />Hooty
 
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GWInvader

Cadet
Joined
Mar 29, 2003
Messages
11
Re: 10' GWInvader with 70 h.p. Merc Help

hey! thanks guys for responding so quickly. I appreciate the help. Yup, my plan is to get a tach. and have my buddy come over with a GPS. I'm not too concerned about the overated thing.....I only take my friends, but thanks for the word of advice, always nice. I think i'm going to end up putting some weight in the bow to keep it down to help it plane better. <br /><br />Do any of you have any experience with a torque shift prop? I got some info. from land and sea on them.
 
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Hooty

Rear Admiral
Joined
Oct 2, 2001
Messages
4,496
Re: 10' GWInvader with 70 h.p. Merc Help

I know they cost a bunch of doneros.<br /><br />c/6<br /><br />Hooty
 
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steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: 10' GWInvader with 70 h.p. Merc Help

Ive heard they are sensitive to dirty water conditions.<br /> There was a used one on ebay the other day<br />price was around $750.<br /> The performance sure is impressive.
 
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