need opinion on 72 18hp speed

[popsmazz1]

I took my newly bought motor out for test run, it"s on a 16ft starcraft that is preety heavy because it has wood floors and a wood platform in the bow. also has a 3hp trolling motor and a battery on it. according to the gps it ran 20mph wide open. is this about right? also has a 9x9 prop on it, is this the proper prop?

 

[gm280]

Re: need opinion on 72 18hp speed

Not knowing the actual weight of your setup, I'd say an 18 HP engine pushing a 16' boat is not bad...

 

[lindy46]

Re: need opinion on 72 18hp speed

Sounds great to me.

 

[AlTn]

Re: need opinion on 72 18hp speed

+1 with both

 

[jbjennings]

Re: need opinion on 72 18hp speed

Same here..... she's running good!

 

[kfa4303]

Re: need opinion on 72 18hp speed

Sounds good to me too. I run a '66 20hp on a 14' tinny and get a little over 20mph myself. You might be able to get a bit more speed by dropping some weight and/or adjusting the height/trim/tilt of the motor. You want the anti-vent plate, located just above the prop, to be level, or slightly higher than the keel of the boat. Generally speaking, the 18-20 hp models were some of the best pound-for-pound motors ever made. Here's a handy link.

Maintaining Johnson E & FD Serie

 

[popsmazz1]

Re: need opinion on 72 18hp speed

actually this motor has a longer leg than the standard longshaft, I have a 78 johnson 9 9.longshaft and this one is 3 inches longer, the cavitation plate is about 2 inches below the hull, the transom on my boat is 21 inches, that might be slowing it down a little.

 

[kfa4303]

Re: need opinion on 72 18hp speed

yeah, OMC motors of this era had sort of an odd length of around 18" with an option extension kit. My motor sat a bit low on my 15" transom so I had to build a little riser to elevate the motor to the right height. I'm not sure it made me much faster, but it did improve the draft and lighten up the steering.