311 Top Speed Question
 

I just picked up an 88 311 with 420's. I put it in the water today and went for a little run and only got about 55mph out of it. It has the factory 21p 3 blades on it. I was at about 1 on the tabs and 4 on the drives. I could spin the motors right up to about 5,000 no problem. I know it would go faster if I gave it more time wide open but I didn't have much room and really didn't want to wind it out for any length of time quite yet. It is bottom painted but its clean, no growth.

My question is I thought this should be a high 60's boat so is the bottom paint hurting me that much, I thought it was only a few mph. I was planning on taking it off anyways.

also about 1/2 fuel, six people, salt water, pretty calm, stock VDO was verified with my buddy's phone.

Thanks

I am spinning 23's and 25's on mine. I change them from time to time depending on what I am doing. I like to run the 23's most of the time. I can get it up to about 69 with a best or 72 on the speedo. The speedo in my boat is fairly accurate. I trim it up almost off the indicator for max speed runs. Tabs all the way up. I have the same year as you.

The bottom paint is not going to loose you much speed if any. People get all worked up about it but honestly if you are going to leave your boat in the water you are better off having it. Your boat will be faster with the bottom paint then with a beard of crap that will grow on it if you have no bottom paint. My boat has bottom paint and my buddies does not and I am always faster and his boat is a year newer.

Are you running Bravos on the '88? My '89 311 ran 67 mph all day regardless of fuel/load with the factory 365 hp 454 magnums and 23p Mirage props.

You are way slow. Mike turned 26" Bravo 1s to 4800 and 70 mph with stock 502 MPI's (415hp). My buddies 87 with TRS drives and 330's would run 60+ all day long.

88 420 boat would be TRS

I imagine its a combination of things, props a little too small for top speed, engines may be a little tired, drag of TRS drive and tranny compared to a Bravo ,and not giving it enough time/room to get those last few mph.
In my case I get to 60 quickly but it takes a while and lots of trimming to get that last 8-9mph .

It is a TRS boat, motors have just about 500 hrs, but pulled real strong the whole way. That pretty much answered my question, thanks. I'm just used to my fathers Fastec that pretty much gets to 70 as fast as you can push the throttles. I guess next year I'll just give it more room to run.

Thanks

Try and find some 24 pitch Bravo 1 props.

My boat will run 68 all day with 25p 3 blades. The best ive seen is 70.8 gps with just my wife and.

311 top speed
 

My '89 with 454 mags and Gill exhaust will run 65 to 66 with either 24" bravo ones or 25P mirage 3 blades.My buddy had an '88 with 420's and trs and the boats would run dead even at WOT.60 mph comes up quick, the last 5 take some room and some trim/tab adjusting.