Stern heavy????

[matt36272]

Hello all and thank you in advance for your help. I own a 1988 305 sedan bridge and love the layout of the boat, lots of room, basically a floating condo. That being said , I can not afford to use the boat! It has always struggled to plane, and when does uses 30- 40 gph!. ive changed props cleaned the bottom, tuned the engines, tried all I know. I once read that the boat is stern heavy and is a design flaw. My question is, is there any fix?

 

[fwebster]

What you notice is common to all small sedan bridges…the shorter they are the worse the problem seems to be. It isn't a design flaw, unfortunately, it is the nature of the beast.

 

[NorCal Boater]

I have a good friend that owned a 1985 340 sedan bridge with small block motors. He had the same problem. His solution? He used it like a trawler and never cruised faster than about 10-12 knots.

Enjoy the scenery.

 

[FLSunfish]

We have the 89 300db. it's the same as yours and with the same issue. We're actually living on the boat permanently now, and when we take it out, we do like NorCal Boater says and run it at trawler speeds most of the time.
But it is nice to know that these boats will run faster if you have to. The trim tabs will assist you in getting the boat on plane quicker and allow you to back off the throttles to keep it up when used properly, but it takes a little bit of practice. Be a little careful while learning to use the tabs. My husband buried the bow pretty good one time when he brought it down too fast. It was a quiet day back in the bayou while we were working on using the tabs and steering just using the shifters and throttles, so we were ok just didn't have any doubt that the tabs were working!

 

[Richard Martin]

I have a 1988 305 with the same engines, and i'm trying to find better props for more speed,any suggestions on what works best for you,and would a 4 blade prop work better?

 

[Happy Hour IV]

Although my boat is substantially different (340 with big block v drives) the stern heavy issue is the same. My engines are way back, Fuel tanks are aft of center, generator is aft of center, dinghy with motor are on swimstep. Many years ago I installed Flow scans and to my surprise my best economy was at 3200 RPM. I had suspected it would have been way lower. The problem with 3200 RPM was with keeping on plane even with full tabs. So next I installed much larger tabs and voila, it would now stay on plane easily at 3200 and fuel usage went down. So next I decided to lighten the boat by removing 200' of anchor chain. Bad idea as she would barely stay on plane. I also noticed a positive change when I ran with empty water and almost empty fuel tanks. Then I moved the dinghy and motor forward.

In conclusion, install fuel flow monitors so you can calculate MPG, lighten her up from center to aft, and move weight from aft to forward. Enlarge tabs as needed.