cyrus77

iTrader: (4)

Scarab 33 AVS- Doing Transom the transom, Should I raise the X dim? (530 dyno hp per side and bravos w/ 4blades, )

c_deezy

iTrader: (1)

Where are they currently? If it will benefit, absolutely.

Team Archer

Yes you need to raise the X dimension Wellcraft was very conservative with the X

hullofjustis

iTrader: (1)

Don't go to high or you will have to deal with the bs i have been dealing with.
But absolutely raise the x dimension you'll the ride, did you say you will put 4 blades on it now?

Where is your propshafts now?

cyrus77

iTrader: (4)

I removed the transom assemblies before measuring where things were. ( I figured i would use the old holes when I replaced the transom.) After reading about things I am interested in raising things. I will try to measure things tonight.
As far as I am have found out:

1. the more blades the higher you can run drives.
2. More blade is harder on drives
3. The faster you go the more benefit raising the drives.
4. X-dim should be around 17.5" for nice all around performance, which results in 4.5" centerline of the prop shaft (correct?)
5. Y-Dim distance between crankshaft centerlines on a twin engine boat. It is 34" on BBC without tall decks.
6. If you run extension boxes you can lift the drives more.

Keith Atlanta

The X goes up and the engines go up raises the center of gravity.(if you use stock drives) Wouldnt it be better to do boxes and or shorties or both?

Also, do you have enough room under the hatch?

Tinkerer

I would raise it 2 inches. If you are running three blade props now You have to go to four blade props. You can always shim it back down easily. It is hard to raise the drive. Most performance boats need to go up at least 2 inches. I went up 2 inches with my 34 Scarab and it helped handling drastically.
I just installed a box on my Daytona and went up another inch. If you want to talk about a high X dim. - last year it was at 1 inch, now it is at 2 inches ABOVE the lowest point of the hull.

scarabman

iTrader: (1)

Several good points in here. I agree with the idea that if you are doing the transom, raise the X, as you could always space back down. That being said, with a Bravo application, once the prop starts surface piercing, IMO, drive longevity starts to get a lot more questionable.

cyrus77

iTrader: (4)

Ok here are some images. The transom has been replaced but not cut.



Notice how little room there is above the exhaust holes. I am not sure how to go higher without buying new exhaust?




So if it is 7" from the transom assembly (gimble housing) to the bottom hull (directly under the output shaft), if I add 9.25" to that I get a 16.25" X-DIMENSION.

If I subtract that from 21.825", I get a propshaft depth of 5.575".

Should this be changed?
Thanks

CIG3

5.57" would be a good start and probably work well. you could always go to a -1 shorty to get another inch if you need it.