I recently purchased a 2003 18 foot Xpress Hyperlift hull with an Evinrude 115 and a Power Tech 20 degree prop. My GPS shows my max speed at about 42 MPH which seems extremely slow and not what I expected. I sold a 16 foot Xpress duck boat with a 40 Nissan last year that ran 32MPH. I just added a Hydro Dynamic 6 inch jack plate and fished with it today in a local tourney but with the tourney and high wind never checked for improvements. A buddy is helping me and thinks moving to a 23 Renegade prop will boost top end performance. What can you guys tell me with experience running similar Xpress boats? I'm not trying to build a racing boat, but want to get the best performance possible out of what I've got. Thanks in advance.
Whats your RPMS and water pressure at Wide open? THats going to help us tell alot. I think you should be getting more than 42mph, probably closer to or above 50. WIthout knows the RPMS or Water pressure its tough to tell. Is your current prop a 4 blade prop? ALot of times the aluminum boats with smaller motors run better with a 4blade prop because it lifts the back of the boat up a little bit and helps hold the bow up. a 23 might be to big, but worth a shot. I would think a 21 or 22, but I'm no expert.
I would buy a 25P three blade, them tin boats run a little better with a three blade. I know a guy who has a 115 on a fiberglass nitro and it will run around 55.
I would call Xpress and ask some questions on getting this boat set up I know sometimes it takes some time on the xpress. Some guys are getting some great speeds out of them.
Hopefully we will get the winds here in LA to die down next weekend so I can do more testing. How do I check the water pressure?
Quote from: Duckmarshal on May 15, 2011, 08:44:37 AM
Hopefully we will get the winds here in LA to die down next weekend so I can do more testing. How do I check the water pressure?
You should have a water pressure gauge on your console
Did you ever figure out the issue?
Doesn't sound to far off for a Powertech prop. They actually like Turbo props pretty well. Ask xpress spanky on bbcboards.net as he's pretty slick with the Xpress setups. My 1998 H-56 with 1998 Mariner 135 does 57 with 2 people(200 & 325 Lbs.) & around a half tank of gas(12 gls.) & a very heavy load of gear. I'm running a Turbo 14&1/4 by 25 pitch. It would actually be a little faster with a 25 Tempest Plus as my props not in the best of shape.
Not sure if you ever figured it out, I have a 2012 H18SS and run a 21p three blade aluminum and bump 50mph on gps. This is at 6000 rpm on the same 4stroke 115hp you have.