Help Me Understand How My Boat's Planing

[rdj735]

Just an update for those who are interested. I was finally able to get my boat back from the shop. However, of the the three "extra" things I'd asked for (new prop, new impeller, raise motor two positions), the only thing they did was the prop. The impeller was fine - I just thought it was a good time to replace, since the lower unit was already off. However, I'm worried that a 4-blade stainless in the lowest position is gonna make for a wild ride, pushing the boat pretty far out of the water at WOT. I'm headed to Guntersville for the weekend, so we'll see...

[J Francho]

9 hours ago, rdj735 said:

Just an update for those who are interested. I was finally able to get my boat back from the shop. However, of the the three "extra" things I'd asked for (new prop, new impeller, raise motor two positions), the only thing they did was the prop. The impeller was fine - I just thought it was a good time to replace, since the lower unit was already off. However, I'm worried that a 4-blade stainless in the lowest position is gonna make for a wild ride, pushing the boat pretty far out of the water at WOT. I'm headed to Guntersville for the weekend, so we'll see...

The only reason to remove the lower unit is to replace the impeller.  All the other work can be done without.  I'd test the new prop as is, and then make any motor height adjustments myself.  You might also think about a prop wrench.  They're pretty inexpensive, and changing the prop is just one nut and a cotter pin/lock ring.  I always kept one with a spare prop in all my boats.

[rdj735]

After testing on Guntersville this past weekend, I think I'm getting closer. With a Solas Rubex HR4 (4-blade stainless 21P), I got to 45mph at 5100 rpm (basically same rpm as before, but with 2-mph increase). Noticeably more lift than my Laser II, and also experienced a touch of porpoising for the first time since I've owned the boat. I think raising the motor will both increase my rpm closer to what it should be, and decrease porpoising. Will be a bit before I can raise it, but will post with results once I can.

[E-rude dude]

7 hours ago, rdj735 said:

After testing on Guntersville this past weekend, I think I'm getting closer. With a Solas Rubex HR4 (4-blade stainless 21P), I got to 45mph at 5100 rpm (basically same rpm as before, but with 2-mph increase). Noticeably more lift than my Laser II, and also experienced a touch of porpoising for the first time since I've owned the boat. I think raising the motor will both increase my rpm closer to what it should be, and decrease porpoising. Will be a bit before I can raise it, but will post with results once I can.

Setting up a motor and prop is time consuming and takes patience. I would only lift the motor on hole at a time. Try it out then decide to go up or not.