What is to be expected? any rpm change? speed change? they work in flat water? what about rough water? safe? not safe? Prop changes? they only work under higher horse power? etc etc. all info is appreciated

I think a lot depends on the hull. What boat are you considering these for?

Formula 353 gains 3-4 m.p.h., 382 possibly 2 m.p.h. Have not really been able to percieve handling differences between boxed/non-boxed 382's. I think it makes a little more difference in 2-4 ft seas. Probably not huge difference in prop/r.p.m. Not sure I would go through the trouble installing these. Bigger bang for the buck spending the money upgrading engine h.p. Mine were factory installed.

38' Scarab, bravo's,502's carb. Upgraded HP is next winters project. time and money and ive got neither,lol

You get more trim with them............take that any way you want. :
D

With high X-dim's they definetly improve the planing. With my cat, I don't even both to adjust the trim, leave it in the sweet spot and the boat planes right off with no slippage. Even with a 3 blade cleaver the the prop only slips for a moment before grabbing. My prop shaft is set to around 1" below the bottom.

Ummmmm .... these would have been good things to ask ... BEFORE you did all the work !?!?!?

You will probably lose about 4-5 mph.

Here's the deal .... I don't think you will see any gains with the boxes until you are at 80 mph or better ??? At 60 to 70 mph the water is coming off right behind the boat ... boxes help put the props in the "cleaner" water behind the "hole"
behind the boat ..... you aint got no hole at those speeds ... so all your really doing is creating additional drag .... robbing speed ...........

Gonna add about 250lbs,,,, one of the Scarabini Brothers is going to stay on shore ,,,,, or your gonna slow down!!

RHC

I would like to thank all the locals wise azzzes for there responses. I was actually hoping to get input from guys who have experience with boxes?