VT18/RT188/TX18 setups

[MattVT18]

I think these 3 hulls are close enough alike that I could get a good feeling from one to the next about what works and what doesn't. I'm having some setup issues with my 2017 VT18. I searched around and found some really good info, just curious if anyone had made changes or not. I am running a Turning Point Express 19P prop. It was pretty good with the engine in the 2nd hole down. I move up a hole after reading several folks saying it helped. I didn't gain anything really. I had my brother (190 lbs or so) in the boat with me Friday. First time I've had a "full size" person with me in a long time. The boat was miserable...top end sucked and handling was bad. Finally just had to let it plow to behave. Couldn't get much above 5300 RPMs. Today I put my 19P Spitfire Aluminum prop back on. I could spin it to 6200 RPMs but speed was only 40 or so. Looked like lots of cavitation as well. What have some of you guys settled on? I probably need to purge a lot of tackle and such to lighten my load, but I was shocked at the difference my brother made in the performance.

[ReefOctopus]

Tagging along.

Im in hole 3 with the spitfire x7 19p and can hit mid 40's but my RPM's don't get higher than 52-5300 (ProXs 115).

[GeauxTide]

Also have a SS Spitfire 19". 44.6 @ 5400 in 3rd hole. Handling is fantastic. Also use a 20" Laser, hitting 46 @5400. Please note, I have an Opti. If you're turning a 4s ProXS 5300, you'll damage the engine. Using a tin prop on anything above a 50 is wasting gas and time.

[ReefOctopus]

Also have a SS Spitfire 19". 44.6 @ 5400 in 3rd hole. Handling is fantastic. Also use a 20" Laser, hitting 46 @5400. Please note, I have an Opti. If you're turning a 4s ProXS 5300, you'll damage the engine. Using a tin prop on anything above a 50 is wasting gas and time.

Im guessing that was directed to me regarding the 5300. How does it damage the engine? What can I do to get the RPM's up?

[n2ratfishin]

I find my analog tach is not linear with my digital SC tach. There can be 400 rpms difference on top end. My analog tach May read 5400 but my SC will read 5850. I’ve never turned my 20 pitch Laser to redline with the 115 4S.

[jrbdad]

Just curious, what engine???

[GeauxTide]

5300 is 1000 rpm off the WOT; however, I just looked at the Mercury site and it states WOT range of 5300-6300. I've only owned 2 Strokes, but would never prop my boat 1000rpm off max. I'd put a 17" STAINLESS and gain 400-500.

[MattVT18]

I'm looking into a 20P Laser II. Mercury did a test on a VT18/115 Pro XS combo with a Laser II. They were able to get right at 50 MPH at 6100 RPMs. I'll try to find the link to the test. Engine was in the second hole down, which would mean I'd need to lower mine back to where I started...

[MattVT18]

This should be the link to the test:

https://p.widencdn.net/uzc72t/115hp-...-18---Laser-II

[MattVT18]

I'd put a 17" STAINLESS and gain 400-500.

I'm thinking about this as well. I can turn my 19P SS 4 blade about 5800 on my Vessel View mobile. While that is fairly close to the 6300 rev limiter, I like to prop my boat to where I can actually hit the limiter before it blows out. I like how the 4 blade prop gets out of the hole and it drives pretty good. Not sure how the 20P Laser II will behave. Mercury's test parameters seem pretty close mine, so if I could duplicate what they did I'd be a happy camper. I've saw a couple of guys having trouble spinning the 19P Spitfire X7, not sure why though.

[Panama]

I won't get into props and RPMs here, but I will just tell you what I would do if I was in your shoes and it was my money and boat.

I would call a good prop shop that deals with props and boats like yours. I have a good prop guy in Florida that builds race boat props and it's amazing what they know and what they can do. I would call Marks Prop Shop ( Mark Croxton) and tell him exactly what is happening. He's been doing this for a long time and seen a lot. Be specific and have your RPMs and how speeds and such handy. He can possibly tweak your prop and help you avoid new prop expense.

These aluminum boat hulls are all different even within the exact same models. They put fiberglass in a mold and they all come out about the same. That's not true with how aluminum acts and how the boat is built. I'd call Croxton and do what he recommends.

[G4bama]

Hard to offer help or advise when we do not know what engine you are running? Are running a 115 PRO XS 4stroke? Is your gearcase a standard or Command Thrust?

[tcesni]

I think these 3 hulls are close enough alike that I could get a good feeling from one to the next about what works and what doesn't. I'm having some setup issues with my 2017 VT18. I searched around and found some really good info, just curious if anyone had made changes or not. I am running a Turning Point Express 19P prop. It was pretty good with the engine in the 2nd hole down. I move up a hole after reading several folks saying it helped. I didn't gain anything really. I had my brother (190 lbs or so) in the boat with me Friday. First time I've had a "full size" person with me in a long time. The boat was miserable...top end sucked and handling was bad. Finally just had to let it plow to behave. Couldn't get much above 5300 RPMs. Today I put my 19P Spitfire Aluminum prop back on. I could spin it to 6200 RPMs but speed was only 40 or so. Looked like lots of cavitation as well. What have some of you guys settled on? I probably need to purge a lot of tackle and such to lighten my load, but I was shocked at the difference my brother made in the performance.

What motor do you have and how much do you weigh?

[MattVT18]

Sorry for leaving out the engine info, I thought I had included it in the original post. 2017 115 Mercury Pro XS 4 stroke, standard gearcase. I weigh about 230. I've left messages with a couple of prop shops, hopefully I'll hear back soon.

Panama - good call on the inconsistencies from boat to boat on aluminum rigs. I hadn't really thought about that until your post. It does seem that very similar setups have different results from boat to boat. I had just attributed it to weight or weight distribution more than actual hull differences.

[MattVT18]

Spoke to a couple of local shops and exchanged a few emails with Mark Croxton. The local shop said they have had the best success with the Laser II 20P. Several others on here had success with that prop as well as the Boat House Bulletin from Mercury. I was lucky enough to find a great used one on here to purchase. Put it on and it was less that great. Called the local shop back and they recommended lowering the engine back to the 2nd hole down (which is where it started and where Mercury/Crestliner tested). Boat is better than it ever has been overall. I still don't get much over 45 mph, but the driving experience is much better. I still can't reach the limiter (or even 6100 RPMs like Mercury did) but I like where I'm at right now. I'm taking the 4 blade Turning Point prop to the local guys for them to check and maybe do a little work. Might take a little pitch out and add a little cup to help carry the loads. I haven't had a full size passenger in yet, but I don't think there will be an issue...the original aluminum 19P prop and engine height worked fine with two adults it was just slow. I'm not saying this is the best set up for everyone, but so far the Laser II 20P and 2nd hole down have been the best for me.

[Panama]

Matt VT18,
Regarding your post above ^^^^^^

When I got my RT188 in 2013, it was one of the first RTs and definitely one of the first with a Yamaha 115. I tried about 7 or so props and had a dealer that was very helpful letting me swap props. I ended up exactly with the prop and setup you have ended up with....second hole and Laser II 20P. I could not find anything that came on plane and ran any better than that setup. There might be something out there somewhere but I bought the boat for the fishability including the room on the front deck and storage and stability.... Consequently, I was not worried about getting another MPH ---- it's an aluminum fishing boat.

I think you ended up with a good setup and the speeds sound about right give or take a little. Most I have seen, including mine, run about like that with a load and in the summertime temperatures. I would be happy with it and go fish. Good job, sir.

[centershot]

2017 Rt188 SHO 115 Spitfire X7 19p, loaded with 2 people and fuel topped off, 5.5 jackplate also.
I run 48 gps. Gonna play with height more and see what I can do. Ive been told I have too much prop slip, analog tach shows 6200. But I dont think its right, digital gauges coming soon

[MattVT18]

Can't speak to the Ranger/Yamaha tach accuracy, but my combo is off some. The analog tach is closer to the Vessel View mobile with the 3 blade prop than with the 4 blade. It's still a couple hundred RPMs low. At 45 MPH I'm turning ~5800, tach shows a touch over 6k.

[GeauxTide]

Not sure how the 20P Laser II will behave. Mercury's test parameters seem pretty close mine, so if I could duplicate what they did I'd be a happy camper.

I turn a 20 Laser 5600, but lift and handling aren't nearly as good as the Spitfire. I agree with Panama - call Mark Croxton's shop. Great folks.