Changing the prop on Tohatsu 6 hp.

Sea Eagle Mark

Seaman Apprentice
Joined
Feb 4, 2019
Messages
49
We're loving our Sea Eagle 12.6sr so far. I can get it to plan with me no problem. But with my wife and gear it's really tough, if at all. So, It has a stock 7.8x8 prop now. I'm thinking a 7.8x7 would be better for the "hole shot" and planing with a heavier load. I'm not concerned about the top end speed as I bought the boat mostly for the 2 of us to have fun and go on adventures. Thoughts?
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Inflate Sib to it's factory recommended working pressure, move wife, load up bow, go for one less pitch. Will work much better than with factory delivered prop which is a medium pitch. The idiotic rule of thumb about props will not work on your combo.

My 2 strokes Tohatsu 5 HP motor achieved + 1K wot revs going one less pitch down from factory delivered one. But will not plane out my 320 Sib with 2 up unless mounting same motor on a much larger 380 Sib. For the record, report if managed to plane out the inflatable combo.

Be advised than when solo boating motor will surely overrev at full throttle, so throtle bit less when on plane. Would suggest to install an induction tach on the tiller grip to check wot revs when boating solo and 2 up.

Happy Boating
 
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Sea Eagle Mark

Seaman Apprentice
Joined
Feb 4, 2019
Messages
49
Hey Sea Rider, yes, I made sure to "balance" the boat and checked the tube pressure before we went out. I plan to get a tach at some point but I've never run any of my outboards "full throttle". I noticed that past halfway you only get a slight increase in speed but, gas consumption goes way up. Plus it can't be good for the motor pushing it to the wall. I've watched a few of Eric Martin sucre YouTube videos as he has a Saturn sib almost identical to my Sea Eagle in size and weight. He also has the same year, make, and model Tohatsu Outboard as mine. So it's an apples-to-apples comparison. Here is a link to the 3-minute video on his prop change and the improvements it made. https://youtu.be/4LD4dDIbjW0. I'm just slightly confused at your explanation on "pitch", so, do you recommend me changing to a new 7.8x7 to help get on plan when loaded? Thanks so much for your help, and yes, I'll post what happened if I change the prop. Mark
 

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Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
SEM,

Very nice combo and perfect deck weight distribution (Thumbs Up) With respect to pitch. If current prop is a 7.8 x 8 you need to install a 7.8 x 7 to increase wot revs to plane combo faster, have better displacement speed at less throttle too. Tohatsu motors achieves their max HP at near full wot rpm that's why need to increase the actual wot rpm.

When ordering the new prop oder an induction tach, would recommend a Hardline Hou/Tach model HR-8061-2. Compact and easy to install. Check Iboats, Amazon. Are you using a tiller extender for the motor ?

Saw the posted video, much better performance than with an 8 pitch, have recommended to install a tach also LOL!!

Happy Boating
 

km1125

Chief Petty Officer
Joined
Aug 10, 2016
Messages
496
If you're not really interested in maximizing top speed, consider the "mouse ears" high thrust prop that they use for the sailboats. I put one on my 6HP and it was like adding traction control. There's less pitch but each blade is larger for more 'bite' in the water.
 
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