First of all I'm new to mud motors. I recently bought a 2007 23 Hp Vanguard Go-devil surface drive motor on a 1548 .125 Legend Craft. I've only been able to get out and mess with it a couple times. The best gps speeds I've been able to get with just me is 16 mph and with 2 people about 15. I dont think I have gotten it trimmed properly yet, but i thought once on plane they would adjust to the optimum level. Also I'm not positive that my rpm's are at the right level, if I remember correctly they were @ about 3300 running full throttle. I have read of people getting at least 20 mph from similar setups. I am going to head to the lake this weekend to play with it some more. Any help would be appreciated.

The very small difference between your loaded and unloaded speed and low rpm makes me think you have the prop trimmed too deep. Turn the trim knob clockwise until the full throttle rpm comes up to 3700-3900 rpm. The cavitation plate should be 2 or 3 inches out of the water and you should be throwing a 3 or 4 foot rooster tail. Unless you have a nasty hull on your boat it should exceed 20 mph with two people. Once the prop is up and surfacing you can tweek the trim knob to get the best speed. When you're happy with how its running you can usually forget any more trimming unless you significantly change load weight or placement. I hope this helps.

ditto - also prop condition is a big factor...

If you are running the GD 3 blade they measure 3 1/2" ACROSS each
blade when new and are worn out at 3" ACROSS....

If it is a 2 blade GD 12x12 they measure 3 3/4" ACROSS each blade new
and are worn out at 3 1/4" ACROSS...

Rebuilding or recupping helps but is no substitute for a new prop....

On a proper light hull you should see about 24 mph solo...

Ok thanks for the response, I will try that with the trim and also check the prop dimensions, I have a 2 blade prop. The guy that I bought it from said he had just taken it to go-devil in Baton Rouge and had them tune it up. He said that they told him the prop was in good condition. But i'll go ahead and measure it also.

Well its raining and dark but it looks like the blades measure between 3-1/2" and 3-3/4" if I measured correctly, that's just at the widest part of the blade in the middle. I didn't check the length yet. The engine also has only 24 hours on it so I'd be surprsied if the blade was worn out, but after looking at the forums it sounds like that would definitely a performance killer.

yea ur blades probly not worn out.. sounds like u juss need to trim it up some.. ive got a 23 gdsd on a 1448 and i run wot 3750 rpms most of the time an do 25 mph on gps

I have a 23 vanguard mudbuddy mini on an old landau 17x60 .08 gauge aluminum flat. Right now I run about 3900 WOT and get 23mph by myself. I'd fly if it weren't such a big hull, but I like the stability and ability to do crabbing/fishing out of it.

When you take off, turn that knob until you start seeing water flying about 5 feet in the air. The handle should become easier to maneuver at this point and there won't be much of a strain on it. Take a little time to get used to the trim and you'll be set. It doesn't run like a longtail.

Had a 15/48 with a long shaft 23HP gdsd Delta waterfowl edition, anything more than two guys and light load had same problem. Myself and my 9yr old it would gps at 23-24mph. with a light load . I was able to get more speed by putting a 4" jack plate on it, I know what some people will say bull but we had a 1654 with the same motor at the camp and it helped out on both. I really think it help make up the difference for not having a 16' boat. But still if you put 3 guys and a load you would push more water than anything. We both had "Cajun Jackers" out of around Lafayette,La. real easy to set, just one nut you can adjust from inside the boat and once adjusted ti had a couple of 9/16 bolts on each side to lock it in place.

I took it out this weekend and messed with the trim and it seemed like the fastest it would go was with the trim all the way down. The rpm's were at 3300 wot. When i trimmed it up while on plane it slowed down. The cavitation plate was running an inch out of the water at most. The rpms were never higher than 3500 even when I had it out of the water. This makes me wonder if I need to adjust the throttle cable, i glanced at it briefly but before I did that I wanted to get some input.

You can adjust your governor while on the trailer out of the water....

Warm up the motor - then slowly roll up the rpms untill it is regulated
by the governor.... Look in your manuak for details - but you basically
just turn a screw to set it... Download the manuals from GD if you did
not get them with the motor...

Set it at 4100 max rpm....

Sounds like your prop was OK - so try adjusting weight front to back - as
many rigs do better with your tank up front... Also what about your hull,
does it have any nasty indentations or irregularities, hooks ???

Thanks for the quick reply, I inspected the hull pretty thoroughly and couldn't find any hooks because I had read that could also be a big problem for these motors.

I'll try setting the governor like you were saying tomorrow and hopefully that will work.

I'm not trying to jack your thread, but I have a problem that goes along with this. I actually have a 24hp longtail. Out of the water I get 4030 rpms at WOT. In the water, I can only get about 3030 rpms at WOT. The hull of my boat is hooked to shit. Would this keep my rpms down? I know it would keep my speed down, I am just curious if it would keep my rpms down too or if my rpms should be higher regardless of what the hull of the boat looks like. Thanks for any help. And sorry if I have jacked this thread, I just though my problem was kind of related.

Mine is a v-bow ribbed semi-v bottom, I'm actually having trouble finding the governer screw or tab, i found the idle adjustment screw. But it seems like that is the problem. I've heard that a 1648 boat may actually perform better with the 23 hp than the 1548 does but that may just be speculation.

And I'm not sure if hooks would mess with the rpms, in my case I cant even get over 3500 rpms out of water yet. It seems like the rpms would be affected by hooks in a similar way they are affected by a heavy load.

I looked for the governor control in the go-devil online manual as well as the paper manual I have, neither gets into enough detail.

And my transom is 16"