tj309

Hello All - I have a 1990 24' Active Thunder Cat with twin outboards on jacks and setback brackets. I think I need to lower the motors 4" or so to get a decent hole shot - at the current lowest jack settings my prop shafts are 1" above the very bottom of the "V" of the cat hulls. To get 4" lower the best way would be to lower the setback brackets where they mount to the transom. My questions are:

1. Is it possible to fill the 16 old holes (8 per side) on the transom to look nice and give some structural integrity back to the transom?

2. How much would this cost me? I am assuming no connections between the motors and the boat must be disconnected - motors can be held close by motor jack stands while the work is being done (?).

3. How much structural integrity will I loose?

Thanks, TJ

DonziDog

If your transom is solid (no rot) you can make very sound hole repairs. The holes will need to be drilled out with a bit slightly larger than the bolt holes to remove all traces of silicone , 5200 etc.Use wooden dowel small enough to wrap a couple layers of fiberglass mat saturated with resin to fill the hole . Just make sure both ends of the wood are covered with glass. This is kinda messy but it makes for a nice job .I've used this method for 30 years with good results. ...Ricky

TablerockToy

Im not sure why you need to go that much lower but .... I think it would be easier to put a spacer between the mid and the lower unit. Not sure where to get these but Ill do some diggin see if I can help

CJ

tj309

Thanks, the reason I want to go 4(?)" lower is to improve hole shot - my prop shop told me lowering the motors would improve hole shot but we did not discuss how much to lower them - yet. I can very easily lower the jack plates 1 1/2" on the set back brackets - without any major work - think that would be enough?

Thanks, TJ

Audiofn

Ya that should be plenty. We have the motors on the old race boat at leaste 1.5" over the bottom and it jumps up on plane no problem.

If you do find that you need to drop the things down then is it possible to drop it enough so that the top holes move to the next hole down and so on so that you only have to fill the top two holes?

Are you sure your jack plate is as low as it can go and also the motor as low on the on the jack plate as it can go?

Jon

FX10

Why not go with a hydraulic jack plate. Lower it for the hole shot, then lift it for max speed. Solves all your problems.

Rick

tj309

I do have hydraulic jack plates. Lining up the holes would save some work, but according to Audiofn the easy 1 1/2" drop should suffice. Yes the jacks are as low as they go and the motors are mounted as low as they go on the jacks

Thanks, TJ

Audiofn

Also no offence to your prop guy but do you know it is not the props causing this problem?

Jon

tj309

Just spent big $ on 2 Hydromotive Q-IV's designed for Bravo-1's. These props are designed to help lift the stern which has solved my excessive bow rise problem during acceleration. I replaced the original racing cleavers and so far am happy with the progress although some work still needs to be done to dial these in. After running these yesterday it is possible no lowering may be needed.