Saber 101
10-16-2011 | 08:25 PM
#81
Registered
Joined: Dec 2002
Posts: 3,363
Likes: 165
From: Providence,RI
Have had best results with 3 blade props, running old school mirage right now. Prop shafts are appx 6.5" below corresponding hull bottom. Maybe your drive or drive placement doesnt allow the leverage to carry the bow well? Or is set for too much positive trim? Trimmed all the way down I get no porpise at any speed, but at low speed any added positive trim will induce a serious propise. I would try a 3 or 4 blade prop if you have an appropriate sized one you can use.
Three blade prop was mentioned to Art Then he Sh@t himself on the idea. LOL. But I think a three blade mirage may be a good call.
There is a ton of positive trim with this drive like you said perhaps
too much.
Thanks for the info. Im curious on the different bottoms????
If you could post a picture of drives tucked all in from side would be great.
Thanks again bro!
10-16-2011 | 08:56 PM
#83
Registered
Joined: Jul 2009
Posts: 1,407
Likes: 3
From: Bay City, MI
I will check the trim angles and take some pics but it will be a couple days since my boat is in storage. The bottom on 28's was changed after the first 3 or 4. The older bottom has a sharper entry and a little different location of the running strakes. There are some pics somewhere in this forum showing the difference, the newer bottom is more rounded and relocated strakes. It was changed to help the boat turn better from what I was told, but the older bottom cut the chop a little better. Maybe Mike will chime in, he has hull #1, big single.
10-17-2011 | 09:51 AM
#86
Thread Starter
Registered
Joined: Dec 2000
Posts: 6,283
Likes: 1
From: EASTON MA.
In my limited experience in testing props, my twin likes bow lift, more the better. I get some porpise at cruise if trimmed out but once I get into the power and get the bow to carry it goes away. Have had best results with 3 blade props, running old school mirage right now. Mine is very responsive to trim, doesnt take much to pick up the bow. Prop shafts are appx 6.5" below corresponding hull bottom. Maybe your drive or drive placement doesnt allow the leverage to carry the bow well? Or is set for too much positive trim? I can check my angles to the transom if it helps, but I know my running range (by eye) is well into negative when buried and only somewhat positive at best speed trim. Trimmed all the way down I get no porpise at any speed, but at low speed any added positive trim will induce a serious propise. I would try a 3 or 4 blade prop if you have an appropriate sized one you can use.
.
10-17-2011 | 09:59 AM
#87
Registered
Joined: Jun 2005
Posts: 517
Likes: 19
From: Bay City, MI
I have the #1 hull and am still in the process of getting things dialed in. Originally my drive was a standard bravo with a deep X of 7 1/2" and running roughly 500hp with a 25 mirage 3 blade I always had a bad porpus when running anything over 4k, would have to heavy tab or tuck drive in to make it stop. I then went up in HP to 750 and running a 28 4 blade it still porpused like a SOB after 42-4300 r's. SO, i changed drives to an XR upper and 2" IMCO shortie lower w/ nosecone and all porpusing went away, maid range to wot. Still looking for a little more bow lift prop and will hopefully be able to get it right next spring. Leaving r's on the table with a 28 4 blade and blowing out a 26 4 blade but bringing the X up to 5 1/2" made all the difference in the world! Doesnt stay as hooked up in the rougher chop like the deep X did but all around a major improvement! Hopefully i can help more if you guys need any other info!! Let me know and good luck Art! Cheers
10-17-2011 | 10:24 AM
#88
coolrunning racing
Joined: Feb 2001
Posts: 561
Likes: 4
From: cape cod
First thing is to check the bottom. Take it off the trailer and get a long straight edge and make sure you know what you have to start. The bottom is what makes it go fast, more horsepower then makes it faster. That being said a bad bottom will run OK with average power, but add more horsepower and it amplifies the problems. Is it porpoising or is it lifting the bow and then falling? One is a bottom issue the other is drive/prop/setup issue? Artie you really should have me put eyes on it.
Jeb
Jeb
