Is 50 m.p.h. the best she'll do ?

7

79monarch

Cadet
Joined
May 31, 2009
Messages
26
I've got a 1979 Monark Magnum 16' 9" bass boat with a 1974 mercury 115h.p. inline six with thunderbolt ignition and all cylinders are between 115 and 120 p.s.i. compression and it has a 21pitch prop. The boat has a strange looking hull I don't know if you would call it a tunnel hull or a hydroplane or what ? The guy I bought it from claimed he had it to a best of 70 but It has a speedo with both mph and kph which I've gotten to a best of 50mph and that lines up pretty good with 70 kph so he may have been reading that it has no tach so I'm not sure what it's turning for rpm's. Anyways yesterday my brother in law drove beside me (about 50 yards out) and according to the digital tach on his jetski we were doing 62. So which is it ? A new tach and speedo will buy a lot of gas which this old motor likes the taste of.
 
7

79monarch

Cadet
Joined
May 31, 2009
Messages
26
Re: Is 50 m.p.h. the best she'll do ?

Here's a pic.
Boatonwater.jpg
 
fixb52s

fixb52s

Chief Petty Officer
Joined
May 14, 2004
Messages
463
Re: Is 50 m.p.h. the best she'll do ?

I would get a handheld GPS reading. Boat speedos are far from accurate. Even new ones will not give a true reading.

Over 50 for that boat and motor is pretty good, probably the max you will hope to get out of it..​
 
SeanT

SeanT

Senior Chief Petty Officer
Joined
Jul 8, 2009
Messages
661
Re: Is 50 m.p.h. the best she'll do ?

Boat speedos are like bathroom scales. Use em, but don't trust em.
 
Bondo

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,526
Re: Is 50 m.p.h. the best she'll do ?

Ayuh,... I'd think 50 is optimistic,... 60 is maybe a dream,... 70 is Not a reality...
 
7

79monarch

Cadet
Joined
May 31, 2009
Messages
26
Re: Is 50 m.p.h. the best she'll do ?

I should've mentioned I'll be thirty in august and have only been around boats for about 4 years. I went out with my brother in law fishing on his boats and fell in love with the water. So early last year I bought my first boat a 12ft. aluminum starcraft and put a 7.5 h.p. on it and went fishing all year. But i quickly realized I liked boating more than fishing so last fall I sold it and this spring I bought this one off craigslist for $300 and after a new rectifier, carb cleaning, paint job, impeller change, lower unit oil change, and some rewiring of the motor this is what I ended up with. So who knows what this winter will bring maybe I'll get rid of this hull and keep the motor for a lighter sleeker boat.
 
W

windsors03cobra

Lieutenant Junior Grade
Joined
Feb 22, 2009
Messages
1,191
Re: Is 50 m.p.h. the best she'll do ?

Yup 50 is it and if you really want to know likes been said, GPS with MPH.

Sweet tower of power, don't beat'er to hard.
 
7

79monarch

Cadet
Joined
May 31, 2009
Messages
26
Re: Is 50 m.p.h. the best she'll do ?

Thanks for all the replies I'm just going to continue to use my speedo and ear for trimming as I have been so far. It doesn't seem to be really turning alot of rpm's but seeing that my hobby before this was low buck drag car racing all I've heard was small block chevy's running 7,000+. I think I'll just enjoy it for the rest of the season and see what happens. P.S. Is this motor capable of better performance on a different hull ?
 
_chris_

_chris_

Chief Petty Officer
Joined
Jul 9, 2009
Messages
439
Re: Is 50 m.p.h. the best she'll do ?

Wow I wish I could hit 30 in my Tri hull.
 
redone4x4

redone4x4

Lieutenant Commander
Joined
Feb 28, 2009
Messages
1,548
Re: Is 50 m.p.h. the best she'll do ?

79monarch said:
Why is that ? 50 seems slow and this boat handles great.
Click to expand...

man, count your blessings at 50 and hang it up. fast enough. thats alot of speed for that hull. i can barely get 40, and i'm happy with it.
 
G

grego

Petty Officer 1st Class
Joined
Dec 12, 2008
Messages
328
Re: Is 50 m.p.h. the best she'll do ?

I am No pro. on hull designs, but looks like a florida lake boat. 50 mph/ yeah MAYBE if you on a florida lake and riding ripples. ON! an open lake you may almost do 45 on a calm day. All the weight looks to be in the rear and an air dam in front, not good topping 2 to 4 ft swells, at any real speed.
 
7

79monarch

Cadet
Joined
May 31, 2009
Messages
26
Re: Is 50 m.p.h. the best she'll do ?

redone4x4 said:
oh that changes things. it'll do 70 easy then based on the front of the hull.

come on.
Click to expand...
I know it won't do 70 I just posted that because it seemed like a couple people thought it was a tri-hull.
 
redone4x4

redone4x4

Lieutenant Commander
Joined
Feb 28, 2009
Messages
1,548
Re: Is 50 m.p.h. the best she'll do ?

no offense man, over 50 and i'd be pleased with her performance, thats all.
 
7

79monarch

Cadet
Joined
May 31, 2009
Messages
26
Re: Is 50 m.p.h. the best she'll do ?

redone4x4 said:
no offense man, over 50 and i'd be pleased with her performance, thats all.
Click to expand...
None taken, I think I was uploading those last pics as you were posting and I never refreshed the page so it seemed like they were in response to you.
 
26aftcab454

26aftcab454

Lieutenant Commander
Joined
May 12, 2009
Messages
1,510
Re: Is 50 m.p.h. the best she'll do ?

seems like a cool unique old boat- I would be happy with it as is- have fun.50mph is very respectable:cool:.
 
You must log in or register to reply here.
Top