First outing in the new to me 1999 29 ol. What a blast! ran pretty good for just having 385's in it. 71 mph on the GPS and the 2 girls up front (were cold...slow down) Anyway this thing has labbed 26 4 blades turning out and 1" shortened Imcos. Is 70 all I am going to see? The engines were @ 5000, full fuel.

yup, that sounds about perfect (with that set-up). Why your running labbed 4 blade 26's is questionable. IMO I would pick up a nice set of 3 blade 27 Mirage Plus. Cut the diameter down to 14.5 (Off the top of my head), thin the piss out of the blades, and you might see 73 in salt water. I think you can safley hit 5250 , but depends on your rev limiter. On a boat like a 29 you won't lose stability by going to a 3 blade. Traditional they are a much lighter prop resulting in less rotating mass. I believe you will get a better holeshot with the 4's but more top-end with 3's. I have a similiar set-up but 496 mags. The late Denis C. at Mercury Racing used the above formula on my props and my best on GPS is 73.8 half tank, two people.

The 3 blades are usually a tick faster
than the 4 blades, but, being you have
1" shorties, they may not bite.

All you can do is try the 3 blades.

A full tank of gas in a 29 adds
900 lbs. of weight to the boat,
that extra poundage is worth
a couple mph.

Unless I'm running a long distance,
I never carry over a half a tank of fuel.

I had 3 bades on my 302 with the same power and also turning out. They were way to small, 23 mirages and not only would they not bite but they would blow out alot. Also tried 25's and they were doing the same. Now I run 24 4 blades, stock, and they run about 68-69 but I have much better midrange, boat balance and I can plane about 5 mph slower. The 4's give you alot more stern lift.

I like the 4's in rough water better too they hook back up much faster and the hold the boat in tighter. Just my .02, worth a whole lot less.

Well, I did it again today and saw 73.8 on the GPS, little lighter on fuel...still 3/4 tank and just 2 people on the boat. Oh yea the water was a little rougher today, which I know helped air the thing out. As far as 3 blades go, no way would they get that boat on plane, it blows out comming out of the hole but still comes on plane quicker than my old 226.

It astonishes me that so many people are using such different set-ups with the same hull. Obviously the salt to fresh water difference is a factor, I just never thought the boats ran that much differently. 454 mag = 385 hp. 496 mag = 375, My boat came from the factory with 26 4 blades which would run 69-70 on GPS. I put the 3 blades on and ran 73.8 Gps. I have used them since with no problems planning or slipping on re-entry. The only time she slip is when I pass threw a patch of sea-weed. I will also emphazise I am spinning a 27". The 4's are more stable but sometimes it's fun to be lose