Every pic of a race boat has a setback pump. I was just curious to hear the pros and cons of a regular and a setback pump. I have a berkeley "e" pump and I was curious to see if I have a good pump.The only logical answer I could give would be the pick up is at the very end of the hull.So it would get more water! Or the hand hole is outside so its convienent.I dont know I am just guessing, so someone please feel free to step in and correct me.
More setback = more weight to the rear of the boat = less wetted surface = more speed. You also get more room inside the boat. Your E pump creates more room in the boat, but is not great for high speed because it has a steep angle on the intake. At high speed the intake water can't make the turn.
I don't know much but I would think that they are doing this to reduce the amount of wetted surface on the hull. Before the Superstock rule in PWC racing, moving a pump back really helped some hulls and hurt others. This would lead me to believe that it would depend on what kind of hull you have to benefit from a set back pump. I would cantact an expert like Jack @ MPD and ask him what the best settup is for your hull.
[This message has been edited by beached1 (edited June 26, 2002).]
369...the further the back the biting edge of the pump the more of the hull can be freed up.( at the upper end of the mph range). Also with the pump further out the back it gives more leverage on the rear of the hull, to help raise it, as extension box's for an outdrive would. This usually is also the effect of a droop snoot.
Over this winter I did a setback on my Berk 12JG...21 Daytona. I noticed that the water is breaking further to the rear of the boat freeing up the hull that = more speed. True some boat hulls may not benefit from a setback. One of the pro's would know more on that topic.
There was a good thread about the pros/cons of setting back a pump on the Banderlog board a while back. Here is the url:
http://www.banderlog.com/cgi-bin/ban...rum=DCForumID1
Originally posted by SB:
More setback = more weight to the rear of the boat = less wetted surface = more speed. You also get more room inside the boat. Your E pump creates more room in the boat, but is not great for high speed because it has a steep angle on the intake. At high speed the intake water can't make the turn.
More "leverage" too...
I have the JE pump with diverter on an 87 16' Tahiti, stock 350 GM , I would like to know what "high" speed is in relation to this pump so I can build the appropriate spare motor. No sense in building more motor than I need ,Right ? I know this is a relative matter but all input is helpful . Thanks ......mawnster
When you are trying to get every mph out of your boat, one of the things you need to do is free up your hull as much as you can without hurting your performance. With the pump set back, the intake on the bottom of the boat is furthest to the rear as you can get, which happens to be the only part of the hull in the water. If your intake was up from the rear of the boat, your hull would have a larger wetted surface, causing drag. By setting the pump back it doesn't create leverage, because you generally would want your motor more forward, not at the very rear of the hull. If your motor is at the very rear, it will drag the ass of the hull into the water slowing you down also. It is safer having the motor all the way back, but for speed, you would want it more forward. Every hull setup varies, but I've seen anywhere from 8" to 18-20" infront of the pump. I hope this helps.
HBjet
[This message has been edited by HBjet (edited June 27, 2002).]
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