Is your boat set up with 700s & NXT drives?

XR lower

Ok that makes sense being at 4.5" +/- with standard XR's. That is roughly were my Active Thunder was as well.

yes

I finally got the boat home. My prop shaft depth is 1" below the transom, that is with -2" sportmaster drives.

How far back from where the water starts rising?

I believe the general rule is 1" of water rise per 12" of set back, the ITS box is 7" of setback. I didn't measure how deep the notch is, I can do that tomorrow. As it is set up now, it walked on plane with 4 blades when I sea-trailed it. So it is certainly not overly aggressive as it is.

So it doesn’t take you 4 miles to get on plane like a fountain? Lol. Kidding aside, if you’re -2 now with 4 blades thru hub, you still may be too deep with the scx-4 and cleavers. It’s boring but probably best to talk to cigarette and find out what their X dim was with the nxt drives. While you’re at it find out if it’s the same as the #6 too.

I’ve ridden in a 700NXT 39, it didn’t just jump on plane, you got it rolling, they would break free and stir for a bit, then hook up and go

I doubt Cig was installing the ultra svelte NXT lowers with the gear cases down that low, so I’d say too that the - 4’s are the way you’ll have to go.

My boat, obviously a different bottom and brand entirely but with the -2’s I’m 1” above the bottom. With 15 5/8 5 blades it gets on plane reasonably well.

I'm not interested in having the drives set so high it becomes a newly developed skill to get it on plane. My AT, had the drives really high for the hull, they were 4" below. With 4 blades it was insanely tough to get on plane in rough water. I do not want to set the boat up to respond like that, even if it means giving up a few MPH. However with the AT, a few guys added a 1/2" spacer and not only got on plane better, but also gained speed. With that boat, I switched to 5 blades and it solved the problem.

I measured the notch this past weekend, it's 12" deep. Hopefully Michigan lifts the no motorboat rule on May 1st, then I can put this in the water and do some testing.

check with Quinlan on here his is a 38 but has full scx

On my 2008 38 i got rid of the bravos and did full SCX drives
with the SCX drives it got on plane so much better it was amazing
i then went to labbed props and ended up having the same speed as when i had the bravo drives,

I put the 1-1/2 or 2" spacer in my full SCX. Never had an issue getting on plane. Even when we took the spacer out - surprisingly it wasn't much more difficult getting up than w XRs.
I thought it scrubbed more speed originally but I wasn't trimming out the drives far enough as this past fall I pulled my best speed to date.
Still trying to figure the best prop. The last one was 29 Herring 5 blade Pushing 6K rpm w 725+hp. Would really like to try some 31- 5 blades. Mine are Bravo style props

Also curious who has some real world time w the SCX-4s on a 38T/S

Best part - NO Drive Failures :flag:

Do you ever run 4 blades with your setup? Can you comment on the differences? I am on the other side of the spectrum, and considering going to 5 blades for usability.

I know its a different boat but I have the SCX uppers with SC lowers and running 700+hp. I have had great luck with them over the past 8 years. Rebuilt them once due to cone clutch sticking and something else minor on the other (forgot) - neither was catastrophic. Make sure you get the right height, one reason I didn't do the SCX4 was the raised height and would have needed the spacers, second was the cost of #6 props and the fact I would maybe only gain a couple mph. With the 5 blade Herrings I run now, I jump on plane and still see 110. I played with other props and got it up to 115+ but had lousy midrange and took forever to get on plane.

https://cimg1.ibsrv.net/gimg/www.off...d5964e7524.jpg

It sounds like the SCX is the way to go on a 38 TS. The one guy that wrote about going from XR to SCX on his 39, reported the same results. 1-2 mph loss in speed, and that was with a full SCX drive. Hopefully someone has some results with the SCX-4.

There are only (2) 38 T/S that I know of running SCX4’s and no 39’s that I know of. Personally, I wouldn’t be the ginnea pig and try it. Go with the SCX Upper and you can always change out the lowers.

Fire Escape- the 39 that Lipship set up is running SCX-4's. That is the only one that I can find, and the past owner doesn't appear to be on OSO anymore. I've messaged him, and never heard back. I am leaning toward the SCX upper with my Sportmaster lower. That would be a pretty easy and budget friendly option. It is also what Fred at Imco recommended.

So going this route where does that put the prop shaft +1 ?.....meaning 1 above the bottom

You had to install the SCX ITS helmet for the set up correct.

You’re right, I forgot about Todd’s old Fire Escape.

If your 39 gets up on plane pretty good now, and your whole point of this is to have a beefier drive....I would go as IMCO recommends with SCX Upper and Sportmaster Lower. The X shouldn’t change. If it is harder to get on plane you can always put a spacer in. You can always swap out lowers and discussed earlier with SCX Upper.

Quinlan-what gear ratio are you running with your SCX’s?

I'm running 1.50 with my XRs.

Sorry, I was asking Quinlan. I edited my post.

Sounds like Quinlan and I are running close set ups. Mine is a TS 725 hp and 760 Trq. Running SCX’s uppers with SC lowers (-2” w/ 1.34 ratio). Already on second lower gear set. Both motors are out getting refreshed. Just order Drive Guardians hoping to keep from eating up lower gear sets. Bravo I w/ 31 P. I run in Gulf of Mexico and the waves can be a bit unpredictable and it’s hard to keep props in water.

My regular props are 32 Bravo 4 blade. I really thinkg I have not trimmed the drives out enough as I did w the 5 blades because it was end of season run when I was testing them incase something Broke. I was testing with a friends set of Herrrings.

1.50 gear sets.
WIll be back on the water Soon- Carter?? lol
Started replacement of all gages and dash panels this winter- then this Dam Virus and switches were coming from China-:angry-smiley-055:
So he is putting it back together with what I had and splashing Soon! We did take out the spacers in the drives. Among several other things .

Let me ask this, what is the cost on the SCX 4? new or used?

Is your boat setup on twin drive shafts or is the read motor plug in?

If youre already double drive shaft, i would find a pair of NXT or 6's and hang them off the back. Of course the imco option is total plug and play, but for that investment, i would think a 6 or nxt would be better option. What is considered bigger at this point? an NXT or an SCX4?

I ran a set of the first scx 4 on a fountain 35 side by side. The bullets are huge. They resigned the skeg to try to offset the drive trying to ski off the bullet. If I were to do it again I would use the scx upper and dual downshaft lower.
Remember if you have a staggered setup the input shaft on the forward motor will be the weak point. Seen a few twist with aggressive setups. Maybe consider drive guardians?

Both of these drives require a transmission which he doesn't have.............its a bravo boat,

I have considered the NXT, however it is a lot of work to convert vs an SCX. Plus the NXT transmission is a weak link when you get over 700 hp, and if I had to guess, in stock form, the SCX is stronger. Yes you can replace the NXT transmission with the BAM conversion but that is $15k plus. If I could find a good deal on an NXT set up, I would consider it. As far as costs go, SCX-4 used maybe $22-23k. SCX uppers used- maybe $16K.

The Six is just too heavy. They only made a few 39 with 6's. The Bravo and NXT boats are better balanced. Plus with the Six, you would have to move the engines from a full stagger to a short stagger. There isn't room to run a full stagger. I want to keep the engine low in the boat, so anything with a velvet transmission is out. Otherwise, I would have installed the Arneson setup I had. That would clearly be the best option, but that is way too much work!

So the best option for this boat is, SCX or NXT. If I leave the engines as they are, maybe Bravos with Drive Guardians.

just to clarify a couple things, a number six 39 is not too heavy at all. Actually they are better balanced in every way. They get on plane almost instantly and are a couple mph faster than a nxt boat. Most people think the opposite but it just isn’t true, the bullet on the 6 is just so efficient and gets through the water so well. Every 39/700 boat built after 2012 came with 6’s so there’s more out there than you think. I agree for you the best and easiest option will be a scx upper and whatever lower you choose. It’s a proven setup, the prop of choice seems to be a labbed 32 maximus

Gee thank you... Adding some transmissions isnt the end of the world as if its dual drive shaft, i would imagine you could shorten the drive shaft to accommodate the trans...

Not all of us are lucky enough to have dads that buy us transmissions...

:party-smiley-004:

There is no way to move the engines forward for the transmissions with a full stagger. Right now, I have 1" in front of the the forward engine and the bulk head. The only way to run 6's in a 39 is to run the engines in a short stagger, or run NXT transmissions. Then if you move the engines, you need to glass the transom, buy new pipes, and many other things. For the HP I'll be running the SCX is just about as good, and I can do the swap in a day.

HA, it is far too easy to let these projects snowball out of control. The next thing you know, you have $100k wrapped up in your drive upgrade. When I looked at the boat, I knew the Bravos were coming off, but the upgrade had to be easy. Sure the ultimate set up might be 6s with NXT transom assemblies , and the BAM NXT transmission upgrade. However, when all is said and done, you would have an easy $100k into that.

I do appreciate the opinions, however, this needs to be a no glass work project.

The BAM trannies also add another 6-7” of set back I believe. That would have to be figured in your X dim then. And then you really have these drives with cleavers hanging out past the swim platform.

To be factual, 700 w/ M6's are full stagger. 850 & 1075 is short stagger.

maybe you should stick to glass work......

the boxes add 6”. The rear transmission sits half inside the box so engines stay in the same place.
very rare for a v bottom to have 2 driveline setups vs 1 plug in and 1 driveline. I know the silver 39 gtx did but again it’s rare

LOL thats odd. My dad works for me now... so, since he runs my books, and tells me what i can and cant spend to keep the company profitable, technically you would be right... i guess he does by me transmissions LOL :whistle:

Gotcha, i was not sure, i figured for the sake of, drilling new bolt holes for a 6 box, and shortening drive shafts it would be a better choice. I did not know it was rare for double drive shafts. or that a 39 needed to be semi stagger. Good luck with your project mike!

Yes, sorry for the delayed response