ScottyChatham

On a 38’ Cigarette Flatdeck what is the correct height for TRS drives? How far below the hull should prop centerline be??? Everyone says raise them a couple inches, but where exactly does that end up?

1983ScarabIII

Watching

Griff

TRS drives were always mounted WAY deep based on the prop technology at the time. I would raise it at least 2". FYI, Konrad TRS replacement drives are 2" shorter than TRS's

ScottyChatham

man’s raising it 2” puts the prop at what measurement below the hub?

BDiggity

On my Cafe, i measured my TRS Xdim @ 17.5". My simplistic measuring had my prop centerline at 8" below hull.

I purchased a pair of Konrad ACE drives to replace the TRS. The standard HP 540 lower is 1.7" higher than the TRS, but mine have the X-Factor's. They are another 1.7" higher than the the HP's, or 3.4" higher than TRS. Using the original drive centerline, i would be at 4.6" below the hull.
I havent had the new holes cut yet, but i am thinking about raising the Xdim another .5 - .75" so they sit 4 "- 3.75" below the hull. The ACE has an extension box so i been told to run mine higher.

1Zoom

B, how far back does the extension box put the drive? I was thinking of switching to the Konrad but I also have a notch in my Cafe, this would change the attitude as well. I may not benefit from the Xfactor.

BDiggity

The box is just under 8" in depth. I dont know the 540 measurements to know how far back the prop sits normally. I am sure its in a diagram somewhere.

In full disclosure i didnt realize what i was buying from classifieds was an ACE, & now doing a bunch more work than originally anticipated. I thought they were regular 540 TRS replacements. But after getting them, i liked the looks of it all & said F-it, i am already putting in a new transom (& subsequently stringers too) i have the opportunity to start fresh. The ACE is a Bravo replacement, so i am having to move the engines back, & then my BW's hopefully mount in the extension box as they would have with the BAM 1350's that come new.

CaptainChazz

I have a similar question. I may post in another thread but I'll toss it out here. 87 Chris craft stinger 390 X. Owner replace the original TRS drives with Konrad's and injected 540s. I'm assuming in the stock location. The boat comes out of the hole OK but appears to be cavitating until it is up on a plane. My initial thought is the drives are not far enough down in the water. Thoughts?

IGetWet

You probably have a good reason, but why oh why if your replacing the transom and cutting new holes etc.. would you be putting TRS’s back on??

ScottyChatham

I am building this as a family boat. I want it pretty stock appearing, kinda like a classic car. The drive’s limit the ho so it keeps me from having a few drinks and thinking I need Big Hp/speed lol. I am only redoing transom and stringers due to the boat being rotten when I bought it. The project grew lol. I even keep the roll pleat interior (expensive) lol. I always loved the drug smuggling classic look. Plus swapping to non transmission drives would move the center of gravity on the boat. I want the best family ride I can achieve with what is there. Raising the drives just seems like a no brainer since I had to do the transom.