Need to figure out what prop?
 

I have the red 1987 Saber Offshore and I just got my boat back from Ben in Grand Haven after being rebuilt. When it was running on the dyno it was @ 500 HP @ 5300 RPM. I put the boat back in the water here in Bay City and with the original Bravo I drive, 1:1.5 gear ratio, and a stock Bravo I 22 pitch 4 blade and was only hitting 5,000 RPM and running 60 mph, using gps.

Just wondering what other 28's have for power and prop and at what rpm they are turning. This was also with a full tank of gas, two people, and on flat water. Drive trimmed properly and tabs up.

Any comments, suggestions would be appreciated because I would sure like to get over 60 :D :D ... MIKE.

Re: Need to figure out what prop?
 

If your #'s are correct ( which I would assume they are considering it was a gps reading.) you have 13.6% prop slip ,
which is not the worst in the world for a heavier 28' deep V,
but it could be a little better.
If 5,300 rpm is your peak rpm goal your prop pitch is probably about right considering you had 2 people & a full tank of fuel. Just courious how much fuel does it hold ?
Do you have any idea how many inches your prop shaft is below the bottom of the V on the hull ?
The guy who has the all white 28 single 502 w 415 hp told me that his boat has a 23 mirage on it.
How much tourque did your motor make ? Also what is the engine combo ? CU" , compression , heads , intake , carb , cam , exhaust ect..
Also do you know exactly what your boat weighs ? Anybody know if the lamination schedual has always been the same ??

Re: Need to figure out what prop?
 

Weights for all the 28 singles is very close but the first one is always the heaviest. i will see if Doug has the original weight. NK

Re: Need to figure out what prop?
 

I figured that the first may be a little heavier, I am curious about the weight. I would like to know what mine weighs minus power ??

Re: Need to figure out what prop?
 

I have'nt had the chance to weigh the trailer by itself but the boat & trailer together weigh 6300 lbs with about 20 gallons of fuel in it. Trailer is a steel tandem axle which I assume weighs approx. 800 lbs if I had to guess.

On the dyno, my peak HP was 499 @ 5400 and my peak torq was 531 @ 4700. At 5000 I am at 489 HP w/ 514 torque.

Also, 5300 RPM is does'nt have to be my goal. I just want to run the engine & drive at hte optimal level. maybe I should only be hitting 5000 r's but if engine can run a little more r's and give a few mph more without running like a rapped ape than thats what I am shooting for. I know with my setup I am not going to be a whole lot over 60 anyways, I will just have to pass people in the chop right :D :D .

Boat has a 90 gallon tank and I'm not sure what prop shaft length is.
Engine is the original 454 bowtie block that has been bored to 502 cu. I believe the compression is 9:1. It has a Dart Hi-Rise intake and IMCO Power Flow exhaust. I am not sure what cam Ben put in it and also not sure what heads are. I just had him build me a reliable turn key engine that runs on 89 octane.

Re: Need to figure out what prop?
 

You really need to find out what your X-dimension is on your drive. ( prop shaft height ) There are a few ways that it can be checked , but one way is to 1) Trim the drive down untill it is paralell with the bottom of the hull ( I would referance it along the cavitation plate. ) 2) Take a straight edge & run it along the propshaft centerline towards the keel of the boat.
3) Measure the gap between your staight edge & the bottom of the v on the boat. that measurement will tell you how deep your prop is running in the water. This will tell you alot about what particular prop will run best on any particular boat.
Talk to you later, Scott

Re: Need to figure out what prop?
 

Thanks Scott. I will check that and let you know. Have a good weekend, MIKE.

Re: Need to figure out what prop?
 

high would be 5 1/2'' to 6''. mine was deep at 7 1/2'' 24degree at the transom. I now have 5 1/2'' much better getting 81 to 83 so far.

Re: Need to figure out what prop?
 

Wieland77 Just wondering if you got it figured out yet? If you need anything let me know. Thanks Parnell 616-437-3852

Re: Need to figure out what prop?
 

I have been woundering the same. I am very courious about that X - dim. that will tell alot about what prop will run best.
If I was guessing it will probably be a little on the deep side for a bravo prop to work best. but we will have to see.