new boat...

Searun1

Seaman
Joined
Jun 14, 2004
Messages
67
Hello all, I am new to the board. I recently bought a 16' '80 Tiderunner with a '81 Johnson 70 HP Seahorse.<br /><br />The boat is made for salmon fishing in the Puget Sound here in Washington. Its is very deep for a 16' runabout.<br /><br />I bought the boat to fish in and also to do a little diving with. The problem is that it really lags when I fill it with gear and try to go diving.<br /><br />I have run it without gear and divers and it doesn't really seem to tear it up as well as it should. To me the engine seems to be running a little low. I have no trim on it or tach gauge. It does take a little long to plane but when it does it does get me up to about 31 MPH on the GPS. I do not know what the pitch/size of the prop is (is it on the prop somewhere?)<br /><br />What options do I have to improve my boat? I would like it to be a multi purpose boat. <br /><br />What should my rpm's be and what does WOT stand for? I have been using my 16' Alumacraft skiff with a 25 hp Evinrude for years and never had issues to learn about I guess. <br /><br />Thanks in advance for any help.<br /><br />Searun1
 

Spidybot

Lieutenant Commander
Joined
Apr 4, 2002
Messages
1,734
Re: new boat...

I think 16' and 70hp sounds a little underpowered. What max hp is the boat rated for (rule of thumb says at least 75% of max should be used)?<br /><br />When tuning your setup you really need a tach (consider www.tinytach.com). <br />The prop specs can be derived from the numbers on the prop.<br /><br />Yuo should reach 5000-6000 rpm at wot with your average load - preferably closer to 6000.<br /><br />When you reach this at wot, your prop is right and your motor will work fine under all circumstances.<br /><br />Provided your prop is in perfectly good shape and does not show any other problems, one inch down in pitch will increase rpm by approx 200. And vice versa.<br /><br />Even if 70hp may be a little low, you should at least allow it to perform as good as possible and it definately should be able to get on plane.
 

Mercathode

Petty Officer 1st Class
Joined
Jun 8, 2004
Messages
210
Re: new boat...

Searun <br />Make sure you tilt-pin is on the 1sr or 2nd hole. If it is set more than that it make be causing the rig to stuggle a bit on T/O.
 
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