help with set up 27 wc
 

I put a post in an other section of oso with no response . I have a 27 wc with a 511 bbc - 2 drive with 28 bravo 4 blade. The boat is hard to get on plane and has a lot of prop slip about 22%. I have had the boat to 65 mph and I know it will go a lot faster .the motor is not straggling at all. I have something wrong or there is a bad Hook in the bottom that is causing prop cavitation . it is expensive to keep making changes ,so if someone has some advice it will be appreciated. I put a 1 in spacer on and it helped some.

Mike , how far up are you trimming the drive ? I keep my drive with the cavitation plate parallel with the tunnels and no further . So I only move mine from 0 to 1 on the trim gauge . If you can post some pics of your setup it would be helpful . Also make sure your prop is true , no bends or dinks .

I can trim it to about 3 on the trim gauge Before it starts loosing speed. The drive is 3 1/2 from bottom of hull. My boat is a v bottom. I have ran smaller performance boats my whole life. I have a 2002 center console allison with 280 on it . I don't know a lot about larger boats but the principals are the same. Some how I'm getting to much air around the prop causing slip and cavation. I was looking at the pad on the boat and it has a hook in it at the transom, I know that on smaller v bottom pad boats like a Allison have a hook in the pad to keep the bow down at high speed, is that what that hook is for? That is a necessity for a 900 lb boat but this is a 4000 lb boat. I made the mistake of removing it from a boat, that's how I know what it is for. If the pad is suppose to be flat that may be what the problem is. The hook is about 3/8 in. The boat needs more bow lift . No one I talk to knows about these boats and can't tell me if it needs to be there. I will try try to get some picks this weekend the boat is pretty tight in my garage and I can't get good pic of the drive.

I have 2" short on mine with a CE high rake 32 I need to use my trim tabs to get it on plane or else it wont plane I get serious prob slip too.

I found part of the problem. The cavitation plate that came with the drive didn't have the triangle filler plate to cover the hole for the ionizer and it was pulling air into the prop on the negative side. When I plugged the hole the boat came up on plane a lot better . Then I added some cup to the prop and that helped so it is doing better but I'm turning to many rpm so I'm going to a 30 p prop with more rake and cup . It is running 70 at 5000 rpm on gps. It will run faster just don't want to turn the new motor to hard it is not broke in good yet. What rpm and speed are you running with 32 and what is hp? It would help if I had a idea of what the boat should run. Thanks

I had some trouble with my 22LXI getting on plane quickly when I first bought it. By accident I put that half moon spacer in the drive lifting rod hole on the "back" side which increased the maximum down angle. Now it lifts the stern much quicker, but I sometimes have to bump the trim up into trailer range when running fast.

In Sarasota it ran 90-91 with a 750HP 572
I jut got the boat and haven't ran it hard on fresh water yet
mines a ex race boat with balsa core haul and gutted cuddy[ATTACH=CONFIG]523603[/ATTACH][ATTACH=CONFIG]523604[/ATTACH]

My 210LXI has about the same hook as yours, causing a slight porpoise above 75mph since I have it propped to lift the stern at high speed.. Trying to understand how to best correct this porpoise I have spoken to several builders about it. While at Phantom boats in Sarasota a few weeks ago I had Will take a look at the hook in mine. His opinion as a builder is it was caused by shrinkage while in the mold, and not by design.
That said, I noted he runs a small wooden block in the same spot on once side of his race boat. Reason is, to stop torque roll... He suggest to fix mine I flip it over and fill only the starboard side, leaving the hook in the port side as that would cause it to run flatter at high speed but no longer porpoise.

As for your speed issue. My slip on a 5-blade 37 pitch prop is 22% and 20% on my 35 pitch. Will thought this was high also, but my shaft speed at 80mph is under 3000Rpm due to the 1.26ratio drive behind the diesel. I'm also running about 3.5-4 inches below the haul, but he felt raising it would hurt stability and only gain 3-4mph at best. Watch my speed fall off the radar gun when I bump the trim up in this video below at 1min 16sec.. Dropped 2mph in under a second with the 35 pitch on it. Inducing air is a speed killer. Sounds like your getting it ironed out..

http://www.youtube.com/watch?v=6l0-n5le4HQ

Hope that helps ya.

Zeke, nice boat you picked up there. I seriously considered adding that one to my dock last year...

Mike what drive do you have ?

Imco Sc -2 , running it this weekend with a full tank and 4 people it is a little hard to get up . I haven't got new prop yet still running the 28 my gps took a puke and can't check speed. The guy that built my prop said that my slip numbers aren't as bad as I thought because it is a little under the stamped number . Can some one tell me about what speed the boat should run with 550 hp . Just trying to get a idea what is good or bad. I had a couple of the baja guys try me yesterday in some rough water and they couldn't run through the rough water as fast as I could they had to let out of it ,I didn't.