Prop For Merc 115 4 stroke

[Boz]

What prop should I put on my new Merc 115 4 stroke? I am mounting this on a Crestliner 175 Phantom. I fish the St. Croix River mostly, so I have always used aluminum.

[ido26.2]

I ended up with a 16 Pitch Mercury Vengance SS on a 1750 Crestliner Fishawk. Overall very satisfied gets RPMS up to 5800, gets me out of the hole, bites well on the corners

[Gilligan]

Merc tecs I've talked to say that for this size motor SS has no advantage other than durability. I have a 19' Starcraft. I could not get the rpm's out of the 17" that came on it. Dropped to a 15" and it works fine. I would guess if I wasn't loaded down it would get 40 or close. Ask the dealer where you bought it, they will usually get you close and may as my dealer did and loan you and extra prop of a different pitch so you can try several.

[Ericp 45694]

Have that 115 merc 4 stroke on a 1700 anler lund. 16 pitch merc stainless. I that that was too small but I get good hole shot and top end around 43 mph gps @ 6000rpm's.

[T-Mac]

With all due respect, I disagree, Gilligan.
It would depend on the hull whether a stainless will be of benefit or not. If you have a well designed "planing" hull, a 115 is capable of good bow lift on a light hull IF it equipped with a prop that can provide the lift. (A bowlifting style stainless steel prop).
A stainless can make quite a difference in ride and dryness on a good hull.

[Gilligan]

T-Mac, you are the prop guy, I'm just repeating what our Mercury dealer told me. If I remember the conversation, I was told an aluminum prop with large hp will deflect but the 115 did not have enough to deflect it.

What would be your thoughts then for my rig, the 15" aluminum gives a decent hole shot and the rpm's I need?

[Goofball]

EricP,

Do you know what your gear ratio is on the Merc 115?

I have a 2002 Lund Angler with the F115 Yamaha. Currently running a 13x19 aluminum. Getting 42mph (gps) @ 5700 rpm. Gear ratio: 2.15:1

People have said that the power-head is the same on these motors, but that the Mercury uses it's propietary lower unit.


Thanks

[Boz]

The gear ratio is 2.07:1, according to the Merc. website.

[T-Mac]

I doubt it would be of much benefit on your particular boat, Gilligan. That is a big boat for a 115. Your tech guys were correct for your situation.

However... :)

The flexing of the blades is only part of the program. Some stainless steel props have cupping configurations that you can't get in aluminum. They can produce positive affects on a boat, if it's hull is designed well for planing ....and if that prop is on an engine that is somewhere in the higher end of the horsepower rating for the boat.

Example: A 1300 lb. "go fast-style", 17' bass boat with a 115 could really benefit from a performance enhancing stainless steel prop. But, the same engine on a 2200lb boat with a 17 degree deadrise at the transom, wouldn't see as much benefit in handling by putting a spendy prop. on it. It isn't the engine actual size. It is the engine's relative size compared to what the boat is designed to be powered with......and also the capabilities (or lack of them) designed into a hull.

[lundeepv]

I have the same boat with a Black Max 13 X 19. The holeshot is great and the top end is around 44 gps. It will unhook on a turn once in awhile when accelerating in a turn. I am going through the big 'D' after 18 years and one of the things on the list is to experiment with a Pirahna prop. It looks pretty easy going from one size to another with this thing and at the rate I go through props (1/year) it may save a little $$ in the long run.