Question on Horsepower

[Fishhunter2009]

Hello fellow boaters.
I am new to this site, and so far it looks like a good place to be for Pro Line owners.
In March of 08 I purchased a 1996 251 WA with twin 150 Mariners. So far I am very happy with the boat, but not very happy with the motors. As usual, when you buy used you are not sure what you will get.
My concern with the set up is that the max hp rating is 300 hp. That seems like a low amount for the combined weight of the boat fully loaded for a overnight trip. I fish the Gulf of Mexico out of Ms, La, and Al. Does anyone else think that the HP rating is too low for this boat? I do not want to go over the 300 hp for insurance reasons. Any recommendations?

[231CALIFORNIA]

No, that rating is about right for the 96 251, its a hefty boat carrying a lot of fuel so it may seem doggy at times. bracket may be limmiter or transom

with twins you are liekly "proped differently than a large single, you have 2legs dragging and you may be propped to run on 1 engine in a pinch(lower than optimum pitch).
 will make top speed a bit lower and fuel economy a bit worse but acceleration a bit better.
yours fully loaded  isoften carrying >1000pounds of fuel , 150+# ice and 2 or 3batteries, a couple cases beer,soda water,tools spares,galley gear anchors, passengers(men 200#average?)food,coolers,tackle,electronics,safety gear etc.
30gal bait tank water ~180#, 15?gal fresh~120# is it 8# or 8.8#per gallon?

are your engines running at right rpm at WOT?, is there any marine growth>.
is your load too far aft or foreward? how are boat and tabs trimmed.? etc.
maybe your engines are "week" 150s.
some guys report  trouble with more moderen(4cycle motors) of approved horsepower becasue of weight.

how does your boat perform with tanks half empty, 2 guys and no gear supplies or tackle on board? do you have a flowscan or similar FFmeter?etc.
If  everything seems optimum then consider carrying less people,ice,gear,fresh water ,bait water etc.until the motors wear out and get some "150s"that have biggerdisplacement or more torque in midrange, boat will seem more powerful in actual use.
Sorry for the long speel, check the props,trim,rpm tune etc and be happy you have a better overall rig than many in the size group, they will sell you a donzi if you want the fast fisherman

[Fishhunter2009]

Well, the top end speed is ok. It is the hole shot that is very sluggish and the mid-range power seems weak. WOT is about 5200 rpm. I keep the motors tuned up and in good working order. I may just need to re-prop, or the motors do not have enough torque for a fully loaded boat. If you are running in 2-4 ft when you hit a wave it does not have the torque to push through, so it will pound pretty hard sometimes. I use the trim tabs to keep the bow in position, depending on the sea condition. I curretnly have 19 pitch mirage props. Would 4 blade props make a big difference on the torque?

[231CALIFORNIA]

4blade will help you with holeshot if its slippage or ventilation/cavitation   related and possibly holding plane if the motors have the right power band.
5200  rpm wot on a 2stroke sounds a bit low to me, what are your motors rated at.
small twins you may have to go down in pitch to get the revs up and to have any chance of planing home on 1motor.
I ran with 4   large /xl men,100#ice and gear yesterday and my 231 used far more fuel than normal and ran slower at given rpm than normal 2 or 3 .
props are your adjustable gearing.
diameter and pitch can make all the difference in  he world. but fuel econ may suffer to improve that hole and mid range or improve if you dont have to push so hard to keep her on plane. can your borrow a pair of props or use some cheap pirahnas or comprops to test, theymight even make 4 bladers.
best to test before you invest in stainless or aluminum  if price is high.
are there any prop shops that will loan /rent you a set  befoer you buy to test?
if they are truly capable of 140hp each  you should have no trouble with the  right props on them IMHO


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• C-Lark III