prop issues

I'm the new owner of Mac Attack and I paid my 25.00 dollars through paypal but cant seem to figure out how to get logged on, anyhow mac attack allowed me to use his logon. On my maiden voyage, I switched props from A2 to A4's and after the first good run at speed I noticed a funny steering issue, I throttled her back and tried again, all rpm no power, trimmed the outdrive up, missing front prop, so I need a set of A4's or a front for spare, Mike informed not good to mix match props, so I have a good back for sale I guess. Help Erik(still the proud new owner of 26' blackman)

Erik,

When you say you're missing the front prop, are you talking about the 3 blade or 4 blade prop. The front prop is a 3 blade and it's closer the the bow of the boat. I might have an extra A4 - 4 blade prop if you need one. Prop sets are almost $700 now.

Welcome to the board!

Thank you for explaining which is which, I am missing the rear 4 blade prop, as well as the cone and bolt, any suggestions on how to keep them from coming off again, mike had A2's on the boat with A4's as spare so I switched them, and first trip I lost the goodies. Thanks Erik give me a call 360-430-9857

Did you forget to tighten the hex bolt inside the cone after tightening up the cone over the 4 blade prop? When pulling or installing the props, you can either wedge a piece of 2X4 lumber between the prop blades and the lower unit to get enough pressure to secure the bolt/nut or you can simply shift the gears into forward or reverse as needed. Just don't do it with the motor running and make sure everything is tight! That's almost a $500 mistake'

I'll check my attic for the spare 4 blade and if I still have it I can ship it to you. You'll probably have to order a new cone and retaining bolt though.

The A2s are a little odd for a 26 Billfisher; what kind of speed at what RPM were you getting? Do you know what the outdrive gear ratio is, either 195:1 or 172:1?

Welcome to the board. I was also looking for a set of spares and Pumphouse said he had a set. I switched over to stainless steel and it was the best thing I ever did. I was having prop flex issues when getting on plane. I do have more horse power than most Blackmans built as an I/O. They can also be fine tuned to your boat and horsepower which is what I did and If you damage one they can most of the time be fixed. i would keep a close look at eBay. They come up often and you can save some coin. I bought my last set of aluminum props from Sea and Ski in Costa Mesa for around 500. That was a few years back.

P.S. Like Jeff said, use a piece if 2x4 to wedge in between the prop and drive. If you have a electronic shift, the gear shift won't work. You can get the prop nut online or if you know what size it is I have a couple of new and used ones here I can send up to you. I think that year is a 17mm but double check to make sure. I check my props and seals every 100 hours at a minimum. I have even had to change them in the water 2 or 3 times. ( NOT FUN in the winter) Once I hit a rock hooping and the other times I have wrapped line in the props. I always carry and extra set of props, center nut and prop cone. Joe

Be carefull not to paint areas inside the prop that maintain contact with the zincs. Check every part for continuity that you install with the zinc using a meter.
Make sure you use lots of marine greese.

Well lets see A2 were getting about 15-16knts, at 3400 I believe I only ran the boat once in L.A. with those props, I believe it is the 172 ratio. Ya i think I found a cone on ebay, A question, is the cone and nut one piece or are they 2 seperate items when I removed the bolt and spun the cone off it appeared as the cone and nut were one piece when I look at the manual it appears as 2 pieces? Also what stainless prop would be appropiate for this boat? Hey honey girl if you got the right cone let me know I take it I'll check the size. Thanks guys Erik P.S. can some let me know who to contact to get my own log in so I can give mikes back.

Just let me know the bolt size, the cone and bolt are one. Try to email charlie (Nomad) to get your log in. I run C3s with a 1.68 and a 300Hp I/O top out at 3800-3900 at 30knts. I run at 3300-3350 at 24-26knts depending on load

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Originally Posted by Mac Attack

Well lets see A2 were getting about 15-16knts, at 3400 I believe I only ran the boat once in L.A. with those props, I believe it is the 172 ratio. Ya i think I found a cone on ebay, A question, is the cone and nut one piece or are they 2 seperate items when I removed the bolt and spun the cone off it appeared as the cone and nut were one piece when I look at the manual it appears as 2 pieces? Also what stainless prop would be appropiate for this boat? Hey honey girl if you got the right cone let me know I take it I'll check the size. Thanks guys Erik P.S. can some let me know who to contact to get my own log in so I can give mikes back.

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If you were only doing 15-16 @ 3400 with A2s, I would bet you have the 1.95:1 lower unit. I have A4s on my Billfisher and 3400 RPMs fully loaded boat is about 21 - 22 kts for me; 15-16 is 3050 RPM with a clean bottom. With Volvo Props, the lower the number the lower the pitch. "A" means Aluminum 3 Blade Front, 4 Blade Rear. "C" means Stainless 3 Blade front 3 Blade Rear. "B" means Aluminum 3 Blade Front and 3 Blade rear, used mostly on gas Duoprops; the "As" are used on the diesel Duoprops. Most guys run A4s with the 1.95 Ratio; 1.95 motor turns for each 1 turn of the drive. Guys with the 1.78 Ratio can run A3s and even get a little more speed at the same RPMs as the 1.95s with A4s. Most 200HP AD41s came with 1.95 drives; the 230-260-300 HP AD42 AD43 AD44 models came with 1.78s. You generally go down one size from aluminum to stainless because the stainless doesn't flex as Joe said.

I would try the A4s and fully load the boat( full fuel, fresh water, bait tank, gear, and 3 bodies) and I would run WOT for a short burst and see if I could get 3900-4000 RPMs (optimum). Caution - monitor your temp guage and do not let it get too hot and overheat. If you get past 90C degrees I would back off the throttle.
If you can't get 3600 RPM out of her then you should go down to A3s and try or put your A2s back on and re-test; if you get over 3900-4000 it's time to go up one size. RPMs and Coolant Temperatures are the key, you should be able to maintain 82C temp while at cruising speed and be able to get 3600 min 4000 max RPM @ WOT.

O.K. I'm on duty tonight so I will get the numbers off the outdrive tommorrow so I know exactly what I got, I talked with a parts guy from coastal marine, and he said I may not have had the "pressure washer" on he said it may have still been on the other prop? Does that make sense about why it may have came off? Doghouse were you able to locate a A4? Also I believe I have the 20mm bolt. Thanks Erik

The cone and bolt are two pieces. They act like one, but there are threads inside the cone that the bolt is threaded through, then the smooth shoulder of the bolt just allows the bolt to rattle around in the cone.

I might have a set of A4s as well. I am picking up a replacement set of A5s for my boat soon. Last set I literally wore out.

Careful of cones and parts on ebay. Most are the older style that requires a lock washer. Newer style setups use a nylon lock nut behind the outer prop. If cone has just a hole for prop tool, it's the older style. If a slot, it's the newer style. Later prop tool comes with wrench/long rod for cone/bolt, and nylon lock nut tightening tool that slides over long rod.

Wizard let me know about your A4's, also is the nylon lock nut your reffering to is that the same as the pressure washer?

Actually, in thinking back, it depends on what model outdrive you have. One prop cone/bolt is 16mm, the other is 20mm. The 16mm setup appears to use a pressure washer. I think earlier models (DP-C and earlier) use the 16mm. I changed out my outdrive to a DP-D, which uses the 20mm bolt/cone and a nylock nut.

Well I believe I have a DP-D the I.D. tag is not there anymore, but it appears to look the most like the D series, so there are no pressure washers, just a bolt, cone, spacer, and plastic washer, thanks for your help everyone, if any of you have spare props or cones, let me know I'm interested. Erik