Hi guys, great forum.

Looking for a little help here. 34 foot Scarab bought last year, runs great, no mechanical issues at all. This is my 1st twin go fast and looking for a little guidance on how to get her up on plane and use my drives to get the best speed. She also has trim tabs, but not sure if i use them or not. Twin 454's tweaked a bit, running about 800 hp. GPS to speed obtained so far was 57. I would just like to know what you guys use to gain the best plane.....thanks

Anybody ?

drives in and tabs about 1/2 down to get on plane.......lift tabs as the bow comes over then move the drives out 2-3 points as you hit 3,500 rpms and roughly 40 mph. Play with moving the drives out and see how it effects speeds. Find the best drive setting for 3,500 rpms.....tabs should be all the way out of the water. Once you find that spot you can push them out slightly more as you increase rpm/speed.

800hp each or 400 each (800 total hp). 57 Mph seems a little slow for that kind of power((1600). I had a 31 Scarab (just a bit smaller than yours ) with 415 mag 502s' and exhaust that put out maybe 440 hp each that ran about 65 on its worst day(70+ on its best) just curious.

440 EACH. Numbers on the motors indicate Merc 440. Both have been rebuilt in Connecticut, but have no specs but the bill with what was done.

What props are you running and at what WOT rpm are you getting with them? What drives do you have and what is your gear ratio?

I appreciate it guys, fairly new to go fast twin screw, half the gauge's don't work but i am slowly figuring out what does what. I feel like I am dragging in the water at times. I know my drives are tilted but I am leary about the k-planes cause they have a tendency to dig when you get into chop. Again......appreciative

I am running TRS's gear ratio 1.5 I think..and BW tranny's... All is stock from 80's except motors were tweaked slightly when rebuilt. I never looked at prop size before I slid it in the water. However...I know I can NOT run these motors higher than 4000 rpm....cause that's all the throttle I have ( and yes I checked...butterfly's wide open).

If it's only doing 4,000 rpms a full throttle then the props are WAY too big. Sounds like you need to drop at least 4 pitch sizes (IE: 28 down to 24)

A neighbor just bought a 19 CC and it was propped all wrong....hit 6800 rpms. Once he propped it properly it runs awesome. Our guess is the seller just stuck on a prop he had laying around.

If you got some props that were less pitch your rpms should go up. You want to have your prop setup so that when you push your sticks to WOT you are running at or very near the motors max WOT range. Anything less than that and you are luggin and overstressing the motor. I think yourmax RPMs for the 7.4l should be 4800-5000 rpm. If you guages are not accurate then I would start by using something else or getting new guages or senders to get some accurate rpm readings. For example: with my 30P 4blade props I can run 5200-5400 rpm depending on the time of year (less in the hotter summertime). My max WOT is 5400 for my motors. If I run some unlabbed 32p 4 blades I usually only see 5000-5100. With some labbing that might go up slightly. Either prop works for me and I actually get better mid range from the 32s but the ideal prop would be the 30s.