I am interested in upgrading my prop from Aluminum to Stainless Steel to enhance the performance of my boat a little bit. I'm surprised that there isn't more information on line about how to recalculate the pitch.
My current specs are as follows: I have a 1972 Formula 233 cuddy. My boat is about 5000 to 5200 pounds loaded up. I'm running a brand new (2020 installed) 357 ci carbureted Mercruiser linked to an SEI outdrive (1:47 gears) comparable to an Alpha One Gen 1 drive (also installed in 2020). I have had the boat for about 9 years and have always used an aluminum Black Diamond 14 1/2" X 19 prop. I am generally happy with the prop, but I am doing more long distance cruising where I go 3 or 4 hours in one direction, and then come back later in the day. I would really love to get more speed out of the boat. At present, I can achieve about 4400 rpm, and am moving at 40 MPH measured via GPS. 40 is great, because on the old motor I could only get 37 or maybe 38 mph.
I just spoke to a Mercury tech who was concerned that 4400 max RPM might be a reason for them to not honor the warranty. He said they really want to see 4700 or 4800, otherwise it means you are over geared and lugging the engine too much.
I don't do anything that makes the hole shot important, like towing skiers. I do boat in very shallow waters a lot, despite always being on the ocean. I regularly have to repaint the prop because I am in sand somewhere and scuff the paint off. Never any rocks, but sand all the time it seems, so I need a replaceable hub in case I need the cushion to not destroy the lower unit. I don't really care too much about fuel efficiency.
If I buy a new prop and end up with higher rpm's but I go slower I will be very disappointed. I would appreciate any input or experience others have had when making the switch from Aluminum.
Thanks
My current specs are as follows: I have a 1972 Formula 233 cuddy. My boat is about 5000 to 5200 pounds loaded up. I'm running a brand new (2020 installed) 357 ci carbureted Mercruiser linked to an SEI outdrive (1:47 gears) comparable to an Alpha One Gen 1 drive (also installed in 2020). I have had the boat for about 9 years and have always used an aluminum Black Diamond 14 1/2" X 19 prop. I am generally happy with the prop, but I am doing more long distance cruising where I go 3 or 4 hours in one direction, and then come back later in the day. I would really love to get more speed out of the boat. At present, I can achieve about 4400 rpm, and am moving at 40 MPH measured via GPS. 40 is great, because on the old motor I could only get 37 or maybe 38 mph.
I just spoke to a Mercury tech who was concerned that 4400 max RPM might be a reason for them to not honor the warranty. He said they really want to see 4700 or 4800, otherwise it means you are over geared and lugging the engine too much.
I don't do anything that makes the hole shot important, like towing skiers. I do boat in very shallow waters a lot, despite always being on the ocean. I regularly have to repaint the prop because I am in sand somewhere and scuff the paint off. Never any rocks, but sand all the time it seems, so I need a replaceable hub in case I need the cushion to not destroy the lower unit. I don't really care too much about fuel efficiency.
If I buy a new prop and end up with higher rpm's but I go slower I will be very disappointed. I would appreciate any input or experience others have had when making the switch from Aluminum.
Thanks
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