A2VeeDub
07-26-2009, 08:33 AM
I am new to the forum so I guess I will introduce myself first. My name is Bryan. I live in Pasadena MD. I spend most of my boating time in the Chesapeake Bay, particularly the Magothy and Patapsco Rivers. My first interest was watercooled VW's (hence the screen name). I build custom turbo engines and such (Not much comparison to the domestic V8's in boats).
Anyway, my father aquired a '72 18 2+3 about 6 years ago. It had been knocked off the trailer in a car accident. The trailer was twisted. The boat had skid across the asphalt. It was cracked behind the rub rail on the passenger side from the point of impact and most of the chines were worn off on one side of the boat. It was sad to see, but good for us because we didn't have the money to buy a "nice" Donzi. It didn't have a motor so he got it for about $2k if I remember. We fully restored the hull and painted it back to the original color scheme. That was our first endeavor into major glass work, and I now have a lot of respect for those guys (There is an expert in the boatyard in our community that walked us through most of it.)
I have since bought the boat from my father, because he bought an '87 22. I think it is the "Special Edition" or something like that. This past winter we redid the half rotted transom and put an alpha drive on with a 1.5 gear ratio. I know you purists would curse me, but the drive was brand new and free. The engine is a half fresh water cooled, aluminum heads, 9.5-1, forged internals, 350ci small block chevy. Guestimate around 320-340 hp. It also has a 100 shot of nitrous. I am currently running a 3 blade 23 pitch mirage prop. Trimmed up the boat did 62 mph (gps) off the bottle at 4400 rpms. On the bottle it hit 5500 rpms at an even 70 mph. Not a bad rpm increase for the 100 shot. Problem is, if you run the numbers, prop slip goes from 7% off the bottle to around 15% on it.
So on to my question. Does this sound common? or should I be looking for a different prop to lessen the slip at higher speeds? The pitch seems right on and if I can get the slip down, I can always up the nitrous dose a little (125-150 shot) to get the same rpm for a few more mph.
Sorry for the long intro. Here are some pics. By the way I have been brousing the forums for a while and some of the info from here is priceless and you guys really know your stuff. Some of the guys picking out years by small details and hull numbers reminds me of the obsessive VW guys I know. Its great.
Anyway, my father aquired a '72 18 2+3 about 6 years ago. It had been knocked off the trailer in a car accident. The trailer was twisted. The boat had skid across the asphalt. It was cracked behind the rub rail on the passenger side from the point of impact and most of the chines were worn off on one side of the boat. It was sad to see, but good for us because we didn't have the money to buy a "nice" Donzi. It didn't have a motor so he got it for about $2k if I remember. We fully restored the hull and painted it back to the original color scheme. That was our first endeavor into major glass work, and I now have a lot of respect for those guys (There is an expert in the boatyard in our community that walked us through most of it.)
I have since bought the boat from my father, because he bought an '87 22. I think it is the "Special Edition" or something like that. This past winter we redid the half rotted transom and put an alpha drive on with a 1.5 gear ratio. I know you purists would curse me, but the drive was brand new and free. The engine is a half fresh water cooled, aluminum heads, 9.5-1, forged internals, 350ci small block chevy. Guestimate around 320-340 hp. It also has a 100 shot of nitrous. I am currently running a 3 blade 23 pitch mirage prop. Trimmed up the boat did 62 mph (gps) off the bottle at 4400 rpms. On the bottle it hit 5500 rpms at an even 70 mph. Not a bad rpm increase for the 100 shot. Problem is, if you run the numbers, prop slip goes from 7% off the bottle to around 15% on it.
So on to my question. Does this sound common? or should I be looking for a different prop to lessen the slip at higher speeds? The pitch seems right on and if I can get the slip down, I can always up the nitrous dose a little (125-150 shot) to get the same rpm for a few more mph.
Sorry for the long intro. Here are some pics. By the way I have been brousing the forums for a while and some of the info from here is priceless and you guys really know your stuff. Some of the guys picking out years by small details and hull numbers reminds me of the obsessive VW guys I know. Its great.