What MPG/GPH for a Mercury 50hp?

[pianorealm]

Hi.<br />Hope someone can give me an idea here. What sort of mpg or gph should I be looking for on my 1985 4 cyl. Mercury 50 Gold Band with thunderbolt ignition? Is there any way to improve it, additives, props etc?<br />It's on a 14ft Fletcher speed boat, if this makes any difference?<br />Cheers.<br />Howard

 

[SeaHorse]

Re: What MPG/GPH for a Mercury 50hp?

6 to 7 mpg cruise, 5 wot.<br />Improve? Spring $6K for a new motor.

 

[pianorealm]

Re: What MPG/GPH for a Mercury 50hp?

Thanks for that SeaHorse. <br />Do you, or does anyone else rate the Hydrofoil fins or 'Dolphins' you can fit to the motor as any good?<br />Howard

 

[fishingdan]

Re: What MPG/GPH for a Mercury 50hp?

I too have an 85 merc 50. I basically agree with SeaHorse's numbers. The numbers can vary due to hull style, boat weight, driving style, etc.<br /><br />Those fins can be good in helping your boat get on plane faster if you are having a problem getting on plane. However, like everything else on a boat, an improvement in one area will take away something else. In many cases, the fins help the boat get on plane faster, but will take away some of your top end speed because of the extra drag of the fin. Some have gotten around that by raising their engine some, but that is too big a job for most.

 

[Moody Blue]

Re: What MPG/GPH for a Mercury 50hp?

Many factors affect fuel consumption but a general rule of thumb is HPx10% to determine GPH consumption at WOT. <br /><br />Hydrofoil/boat/motor applications are unpredictable in how they will perform. Depends on hull type, motor mounting, boat balance etc etc etc. They are relatively inexpensive so many people try them as an experiment. If they work great, if not take them off. As mentioned the primary reason for installing them is to overcome some performance issue(s). Used mine to reduce porpoising. Worked to a point but not completely. Took the foil off and installed trim tabs. Mucho better all-around. An important point to be aware of is that the foil must be out of the water once the boat gets up on plane. If the motor is mounted such that the foil stays submerged, it can cause steering and handling issues (but may not).

 

[laker925]

Re: What MPG/GPH for a Mercury 50hp?

What are the trim tabs?

 

[Moody Blue]

Re: What MPG/GPH for a Mercury 50hp?

Devices added to the transom to improve overall performance of a boat. Generally in the form of metal plates mounted to the outside edges of the transom. These plates are slightly angled into the water and control how the hull travels through the water. The angle of the tabs can be controlled to alter the running attitude of the hull in different conditions. There are manually operated electric and hydraulic types, fixed types and automatic types. Do a search for "trim tabs" using the red "search" feature near the top of the page. You will find more info than you can read in a week.

 

[pianorealm]

Re: What MPG/GPH for a Mercury 50hp?

Thanks for all your replies. Be able to work it out easier now.<br /><br />Cheers<br /><br />Howard