looking for better hole shot

[sirsnap]

I have a 1982 19' cobalt br with a merc. 260. Top speed with the current prop at 4600 wot is 49 (gps). The prop is a 19p stainless not sure what size it came with the boat. The hole shot is pretty weak when trying to ski. I would think it would jump out of the water with 260hp. Maybe i'm expecting too much. Just wondering if i should try a 17p or maybe a different 19.
thankyou

 

[sirsnap]

Re: looking for better hole shot

That is a 5.7l I think i'm pretty close too the right rpm at wot.

 

[Dhadley]

Re: looking for better hole shot

The wot is OK but when you're trying to ski that's a different story. You might try venting the prop if it isn't now. That is if you have thru hub exhaust. If you have thru transom exhaust, venting the prop won't do anything, obviously.

Other than that you might consider using a 15" prop for watersports and use the 19 for cruising.

 

[Texasmark]

Re: looking for better hole shot

I agree on the venting. I had a Ranger deepV padded boat with a 115 merc. Due to the hull design, there wasn't much hull area to establish planing in the first place and then when you add a skiier, what a mess.

Ports solved the problem. Firewall the throttle and the engine revs up due to the bubbles across the blades. In no time you're up and the next thing you know the bubbles clear out and it feels like you just went into overdrive.

A marvelous invention that saves all that prop swapping and allows you to get both the torque and speed benefits simultaneously.

Mark

 

[Almeja]

Re: looking for better hole shot

Take a look at the High-5 (stainless) and Alpha-4 (aluminum) props. High 5 is supposed to be the holeshot king (don't have one tho). Alpha 4 blade has a lot more 'bite' too. Consider 20" pitch in both those props.

Is your engine coming up to RPM rapidly on holeshot but the boat's not going anywhere?

Unless your engine is 'bogging' and not spinnng the prop up quickly, a ventilated prop may not be the answer for your situatoin. They are the cat's meow for getting a low-torque engine like an outboard or small displacement I/O up to speed fast.

 

[sirsnap]

Re: looking for better hole shot

i have thru hull exhaust right now, but i'm considering switching back to stock, Just not sure since it;s pretty expensive. the engine does seem to bog quite a bit when i get on it. After on plane i have plenty of power it's just the hole shot that is lacking. might look into the four or five blade prop. Doesn't sound like porting my current prop will help because of exhaust.

 

[Dhadley]

Re: looking for better hole shot

You're right, porting wont help if there's no exhaust to let out. Unfortunately with I/O's we're limited on set up options (unless it was mounted way high from the factory -- and there's not much chance of that) unlike an outboard where we can easily change the X dimension.

Without exhaust running thru the prop even an OT prop probably won't make much difference. There are some 4 blade props that probably will do what you want though. Perhaps even some 3 blades.

What brand / style ss 19" prop do you have now?