05 searay 200 sundeck

[pacman78]

i have a 05 200 searay it has a 4.3 mercuriser 220 hp i been trying different props but still not hitting top speed. the boat came with a 19p prop i hit 40 mph but barley most time full throttle i was at 36 mph at 3900 rpm. i tried a 17p the rpm were up top speed was 38 but a alarm was going off knocking my rpms down. i have a 21p on it now i hit 42 mph once but yesterday can only get 36 mph at 3600 rpm. i trimmed it up but still not getting top speed. 3/4 to full throttle i only get 2 mph and like 200 rpm out of it and help would be great

 

[Lazy Daze]

I believe the 19" would be the original prop the boat came with, it should be SS, as well. There's a couple common themes with these types of questions, and here are the general answers (which can be found in other, similar threads, as well)...

-- Trimming is not being done correctly
-- Way too much weight in the boat
-- The boat bottom is dirty
-- A fuel issue
-- A mechanical issue

Let's address the first three, before we start down the other avenues.

 

[pacman78]

when i trim i wait till boat is on plan then i trim up to about 6 or 7 its more then half i been playing with it to see where the mph increase and listen to the motor. the boat weights from the spec on the boat 3500 i had 1/2 tank of fuel me and my wife. the bottom is painted on the boat. i want to do a compression test on the motor and maybe plugs wires cap rotor maybe fuel and air cleaner filter. i am trying this stuff tomorrow so any other suggestion to look for would be great thanks