I'm new to the site, but not to lontails. I've been running my homemade stainless steel lontail for about 10 years now. I have a stock Briggs 23HP vanguard on it. The hull is a 14x42 Alweld. I've just always lived with horrible speed. In shallow water I can break 12 MPH with me (240 lbs) and another and no hunting gear. I have the battery and 3 gal. tank in the back. My motor is probably a little heavier than stock since I built it a bit beefier. It's best when the passenger sits on the bow. I'm turning a beavertail 9x7. I'm probably over-propped, but I have great performance in mud and grass. I turn 3380-3400 rpm WOT.

I would like to get a new prop since it is cheaper than a hull. I will try the engine on a buddy's 16x48 soon. Which prop should I try? It would be great to at least hit 14 or 15 MPH!!

Any help is appreciated!!!!!!!!!!!!!!

Backwater 9x7 its actually a little smaller than a true 9 inch

I have a 27 MB longtail (2004) and though rated for a 9x7 prop, I run 2 mph quicker with a 9x6. I think you would do well to try a 9x6, you should be running a little quicker than 12 mph. If you can, relocate the battery to the front. Have you experimented with the "trim tab" on the cavitation plate? You might be running too deep. You can also tweak the throttle to 4000 rpm out of the water and should experience a gain- this won't hurt the motor. I am sure you have inspected the bottom of your hull for any anomalies? MudBuddy and others match the 23 Briggs motor with either a 9x6 or 9x5 so like you said, you may be too overpropped!

Thanks for the replies. I think the cavitation plate is good. It runs right under the surface. When I first built it, I just tack welded it, ran it, an tweeked it. I will try putting as much load as possible to the front. What kind of 9x6 should I get? GD? Hill? Tiger?

I had a 1448 welded MV with a 23hp before. When they started heavy cupping the blades I had to go to a 9X5 (original was 9X7). Turned great. I've had Tiger and GD. Couldn't tell the difference between them. If you don't have a GD motor they won't sell you a prop though.
3300-3400 rpm is low. 3500-3600 is what you should turn in the water. Adjust your cable and govner to hit 4000 WOT.
I could run 15-16mph with 2 guys dog and gear. Put a 3rd guy in and 12mph or lower.

All three prop mfg.'s are good. I found the MB the "stoutest", meaning it wore down the least in comparable conditions- the GD wore down the fastest but I actually gained 2 mph! The Ron Hill prop was the cheapest and is almost identical to the MB Tiger and I have it as a backup. The water levels here are still historically low and during teal season I wore down the GD quickly so I just put on the 9x7 MB Tiger- its cup is greater so I have to tweak the trim tab because it tends to want to kick up more- it actually runs faster half out of the water, but too difficult to run that way! Years ago on my 18 HP GD, I tried briefly a 3 bladed GD prop which was fast in open water but bogged down in the weeds- if they could make a truly weedless 3 blade prop that would be the ticket.

Thanks guys! I was leaning towards the tiger. I've always heard only good things about them.

I can hit 18 mph @ 3450 rpms in my boat all day long with 2 people and fishing gear.

Get you a new prop!