2003 H56 Issues

[MDean89]

I have a 2003 Xpress H56 with an '03 Mercury 135hp Optimax. It has a four blade ss prop (not sure of the brand and it's stamped 251 P with the 5 crossed out, then underneath that it is stamped 19P 251). I have a 6" Pro HI-JACKER manual jack plate and outboard is mounted in the second from the top hole of the jack plate - it can be moved up one hole or down 3 from it's current mounted position. The best I can get is 41 mph and ~5100 rpms. If I trim up anymore from the 40-41 mph range the boat starts porpoising so I have to trim down resulting in slowing down. This is with just me in the boat, half tank of gas, cranking battery in back, live well empty and trolling motor batteries stowed up front with other gear. Seems I should get more speed and more trim range, but I don't know where to start. Hydrofoil, trim tabs, prop? Any tips or help would be greatly appreciated. Thanks in advance.

[Arkyarcher]

Try moving trolling motor batteries to the back. The porpoising is due to prop losing bite, second thing would be trying a different prop.

[MDean89]

I sure appreciate that Arkyarcher. I just moved those batteries to the front last Friday in an attempt to distribute the weight better (boat sits way low at the stern) to see if I could lessen or eliminate the porpoising. When I took the boat out Saturday to test it it did raise the rear a couple inches, but no remedy for the porpoising.

[MDean89]

Current Prop..jpg

[Arkyarcher]

My other suggestion would be lower or raise the jack-plate but you effectively did that by moving batteries so I'm thinking try running some different props.

[MDean89]

My other suggestion would be lower or raise the jack-plate but you effectively did that by moving batteries so I'm thinking try running some different props.

I've gotten quite a few conflicting opinions on moving the batteries to the front. I have a 23P Power Tech 3 blade that I will try. Thanks for the suggestion I really appreciate any help!

[MDean89]

Current Prop..jpg

[Woody60]

Monty, I had the same issue with my H17. To be honest it was just me figuring the trim out. I've learned you have to be gradual when trimming up and I never go above the halfway indicator on my trim gauge or mine starts to porpoise. My top speed with a Yamaha 70HP is about 32 mph. I run a 3 blade prop and my hole-shot is pretty good but my top end could be better with a different prop probably.

[MDean89]

Monty, I had the same issue with my H17. To be honest it was just me figuring the trim out. I've learned you have to be gradual when trimming up and I never go above the halfway indicator on my trim gauge or mine starts to porpoise. My top speed with a Yamaha 70HP is about 32 mph. I run a 3 blade prop and my hole-shot is pretty good but my top end could be better with a different prop probably.

Thank you Woody much appreciated. I just wanted my boat at peak performance.....not necessarily a speed boat, but I know that big ole 135 Opti can push that aluminum boat faster than 41 mph. I don't have the $$$ to buy and test different props so I'm just going to leave well enough alone. I'm going to return my trolling motor batteries back to the rear and go with very little trim ability and let the porpoising be my 41 mph speed limiter. I do have an extra 3 blade 23P prop that came with the boat that I've never put on. Maybe I'll try it one day. God Bless!

[Les Young]

I had a 98 h-56 with carbed 135 mariner that was a dog with a 4 blade. It never porpised but would catch water when trimming up & make you think it was going to jump out from under you to the right until I added a 6" vance plate & a 3 blade turbo prop off of my buddy's old boat. It then would run 58 gps with 2 big boys & a huge tackle load. By myself i could gps 60 & i had a lot of slip with the 3 blade so a better one would have done better. The plate & prop really woke it up after it gave it some lift. It also set low in the stern but you get use to it & other xpress owners tell me the newer trolling motors make a big difference in the blowing around thing which is the absolute only reason i got rid of mine. I'd like to have another xpress but the only one i know of around here is the one i use to own.