I have repowered my '73 233F from twin 120's on a bracket to twin 250 Etecs. I am trying to decide which way to go on props. I know the 233 hull has a lot of rocker in it, but I don't know what props respond well to the rocker.
Has anyone tested either or both of these props w/ their 233? It doesn't have to be the same hp - just trying to get an idea how they both carry the hull.
My understanding is the Rev4 has a little more stern lift (which tends to raise the entire hull) & the Bravo has a little less which keeps the bow up a bit more. These are generalizations though, and each hull is different - would be great to have some 1t hand experience.
My opinion is that 233's like bow lift. You might give Brent at B Blades a call.
Thanks, David. I think you are right. I ran Bravo 24p briefly last summer, & the boat ran like I had the trim tabs down. Very smooth, but too much slip. I think my above comments are actually back-wards. Bravo lifts the stern more, & Rev4 carry the bow a bit better.
I have ordered a set of Rev4 23p based on the advise of someone w/ a similar hull. He found he was able to trim up the bow when he wanted, or tuck the motors in and drop the bow when needed. Fingers crossed its the right combo. I won't get out testing for another 6-8 weeks or so.
Jon I use a single 19 inch pitch Mercury Mirage prop that works great on my boat. I have heard if you double the hp you usually go up 4 inches of pitch. I've tried 4 blades but I lost top end speed with them .
Sounds like I am in the right ball-park then - only difference being 4 blade 23p vs 3 blade. I think I should be able to turn them (hope so), otherwise I will be looking for a set of 21p's.
What do you see for top & cruise speeds with your rig? That black on red looks great!
Thanks Jon ! You should have no problem with the 23's as long as you don't mount the engines to low on the bracket. 4 blades work better higher than 3 blades which would increase efficiency. My boat cruises in the mid 30's and a solid 50 at the top. Even better when in sloppy water and running light. I've had my boat for 25 years and had a lot of time to dial it in just right. I would love to have twins just dont want to feed them !
B Blades has a test program too. I've worked with Brent an he knows his stuff.
Good to know. I was going to go new props w/ a test program to dial in last summer. A blown lower unit curtailed the budget though, so I bought a slightly used set to just get on the water. I will go back to testing if I don't like how they perform.
I'm more concerned w/ handling & efficiency in the 3,000-4,500 rpm range vs top end.
I also agree with David that these hulls like bow lift. There is also a sweet spot with the engine height mounted on the bracket. The Mirage prop gave me excellent handling & effieiency at mid range. I know new props have come a long way since I got mine 8 years ago .
Rick - do you know what your cav plate height is in relation to the running surface at the transom?
I had Brent lab a set for me and I got a great improvement in both handling and fuel efficiency. I agree that you will make a lot of sacrifice if
Its been a while since I measured it but I think its 4 to 5 inches above bottom with 30 inches of set back. The rule fo thumb is to lift engine up 1 inch for every 12 inches of set back. I know mine is higher than that because thats where I started from. The boat is on the lift now and can't get a measurement. I will the next time its on the trailer !