Problem with a Tohatsu 70hp planing

Huntersbane

Recruit
Joined
Mar 7, 2005
Messages
3
Any one got an idea as to why my boat will not plane correctley. <br /><br />she is a Shakespeare Skiman Delux 13ft and I have a Tohatsu 70hp outboard (no Trim and Tilt) with a 10.5 x 13 prop. I have just attached (to the cav plate) a set of fins and she still nose dives at about 30mph. I have set the THRUST ROD to all Positions and still the same. Any one have an answer. Oh i have a 1 inch block ajusting the hight of the engine on the transom, should I remove this thus dropping the prop further?? <br /><br />Thanks <br /><br />P@ul...
 
Joined
May 16, 2009
Messages
6
Re: Problem with a Tohatsu 70hp planing

same problem on my brothers bass master he moved the pin all the way back which moved the prop from the transom an now when he takes off the bow raises then planes out great his prop is about 7 inches below the very bottom of the boat
 

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,559
Re: Problem with a Tohatsu 70hp planing

Rule of thumb is that the ventilation plate should be about level with the bottom of the transom. Likewise, rule of thumb is that the thrust rod should be set so the motor is vertical at normal operation conditions.

Sounds like you are under propped. 13" pitch is listed on the Tohatsu prop selector chart as a "heavy" load prop for a TLDI 70. 10.5" diameter is a bit strange for that motor as well. Is this a special-purpose, or 4-blade prop? Most Factory props for that motor have a larger diameter. Maybe this question is better asked in the prop forum.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: Problem with a Tohatsu 70hp planing

Tohatsu suggests 3 to 5 cm from lower transom to anticav plate for best engine performance, set trim to any hole psition that will give you paralell anticav plate with respect to water surface while on plane. Distribute weight to balance boat properly.

Happy Boating
 
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