I need help finding the right props for a twin outboard v hull.......
 

can anyone give info about getting the props right for a 28 foot v hull that has alot of setback / natural bowllift????

ive been running merc chopper IIs but that is a bow lifting prop, the 2800sx is a "pad" bottom boat and it has a heavy transom due to the 30 inch setback with twins on it so i dont know if i really need a bow lifting prop......

seems like a prop with a little less bow lift and more stern lift would help the boat stay on the pad......

small ear chopper????? cleaver?????? Merc et / hoss style chopper??????

ive got ALOT of conflicting answers to this question.....anyone got an opinion????

in a 28 foot long pad boat....with a TON of natural bow lift.....should i be trying to lift the bow even more??? the boat is very light in the bow even at speed.....

the boat has a tendency to porpoise, this can be controlled with the tabs but tabbing down scrubs speed.....the porpoise is because of the boat lifting the bow and not being able to carry it due to improper pad balance / "falling of the pad" at least thats what ive been told.

as i understand it...with a pad boat....its a balancing act (in this instance in the sense of fore and aft....) the boat is riding too far on the aft portion of the pad IMO....

i have also been told that the deeper your props are (x dimension) the more bow lift the choppers create.....and the more shallow they are = less bow lift.....is that true????

the props were turning IN....and as i understand it this creates BOW LIFT....correct???

so should i turn the same chopper props out in order to not carry the bow so high??

what i have now is a boat that runs great but is unbalanced but is managable with the K-planes........i believe due to the style, height, or direction of the prop rotation......

anybody????????????????????

i guess this is just a mystery....... i cant say that im surprised. lol everybody just guesses at htis stuff anyway.

ive talked to at least 10 "experts" and have gotten 10 different stories about what props give what characteristics, what prop direction does what, what different behavior means.....

kinda like every other field i dig into.....when you cut away the BS and it comes down to it....even the "best in the field" are pretty lame.

fixx
 

sorry i cant help im not a outboard guy..try call my prop guy,,http://www.dahpropellers.com/ ask for john,,he will set you straight..

I tried rev 4's on my 30 scarab sport with twin 225's. they gave me a lot more stern lift than I wanted (she loves to run with a lot of bow lift). Best thing to do us find some folks with similar set ups and talk to them. So what kind of boat and power?

Can you provide more details on your rig and it's set up? How about a profile picture of the stern and one looking at the stern? Trim tab type, size and location is very important. Are the engines on a fixed bracket? Let me know. I run Mazco RE3 props woithout a pad bottom though.

I also need to know how wide your lifting strakes are. I think there are two full length? Let me know.

thanks for the reply!!

the boat is a 1987 2800sx checkmate. (same as the Ocean Outboard race boat that did so well in the 80s)

its got a 30 inch satainless marine floatation style setback bracket, twin 20" merc 200s mounted on 18 inch centers, counter rotating lowers with LWP, prop shafts are 2 inches above the bottom of the hull (measured in front of each bullet)

it has 280 k planes that are mounted 1" from the hull running surface and on either side of the setback bracket (at the same anlge as the hull line, like most v hulls ive seen)

im not sure how to measure the "strakes"......they are 9 inches wide with a 2 inch flat on each one.....the pad of the boat basically runs the entire length of the bottom and there are to "strakes" on either side. im not sure im measuring correctly so let me know! lol

i have only tried running merc choppers on the boat and was turning them "in" but i find myself questioning if i should be running bow lifting props.....turning in to give more bow lift....on a boat that is light in in the bow....and already has a ton of natural bow lift?????????

thanks everybody for responding! looking forward to hearing some input!

max

That's good stuff. LOL
Actually we have propped tons of Checkmates and I have owned them myself. You have a few things going on here. A lot of the information you described in your first post is accurate. Getting the correct combination is the goal. 30" of set back is quite a bit. I'm quite sure the porpoise is due to the propellers not being able to leverage the transom long enough and the CG finally wins and down comes the bow. I've never propped a Checkmate (other than a couple race versions) that didn't want the most bow lift it could get.
If you would consider it, call me and I can go through a bunch of stuff in short order which will generate more questions and it will save typing time.
We also have test propeller options which may answer some questions only answerable via testing.
Sorry for the delay in answering.

Brett
920-295-4435

lol hey brett!

you are actuaLLY one of the only people that seem to offer consistent information. i appreciate your time.

i will call you and see what we can do....i have noticed that my boat rides with the bow high in the air and on the very back of the pad....even with the k planes down.....

i cant tell if i need more bow lift.....or less bow lift.....lol

more cup wold make the props bite harder and givemore ability to carry the bow...... but my bow is already so light it just seems counter intuitive since i would like the boat to fly flat and not bow high....