Chris,

That's very encouraging! How does your heat do at 3.5 with a bravo style 4 blade? I'm just looking for comparables.

Thanks for replying,
Jon

Jon,

I have trouble hooking up a four blade on the bottom end at anything less than 4". But, the Rage is lighter, and might not have the same problem. As I said above.. my boat is the fastest at 3"-3.5" with a five blade. Also, the shorter I went, the less chine walk I had at top end, but gave up some low to mid-range cruise speed. At 2.5" my boat handles like poo at all speeds.

Every boat is different.. I have come to realize that my 600sci is the heaviest motor they have put into a Heat... well, untill they put the 700sci/NXT package in the red boat.. but they are still trying to sort out the handeling on that boat.. I think

Anyway.. keep going shorter until it just doesn't work.. the boat will let you know when it is in its "happy place".

Chris

Try the -2 Jon while you have the chance. You never know for sure what will work until you try it.

Do you have access to any five blade props of appropriate pitch to try with the -2? Just a thought based on Chris's experience with low X dim.

Chris,
You were right on the money! 5.5 wasn't much different than 4.5, but 3.5 rocks! I got a best of 86 @ 5700 with the merc lab 28 B1. The boat was slightly slower to plane and the prop wanted to blow out if I got on it too fast. It liked less trim, but felt great at WOT. With this lower I didn't have a cavitation plate, maybe that was why it wanted to slip when coming on plane. It feels light and throws quite a roost even when cruising.

Told ya... :evilb:

The roost is because you are now surfacing the prop.
Handeling should be more stable on the top end because the prop does not have as much "side to side" leverage on the boat.

The cav plate will help getting on plane.

A 27 P5x will hook up like glue on the bottom end, and probably give you another 1-2 mph on top.
A 15" 27 pitch Hering will come on plane about the same as the Merc Lab 28, but will be about 2-4 mph faster than the bravo on top.

Chris :ernaehrung004:

I almost bagged the -2, glad I didn't. Thanks for the support! I found a 27 P5X, but didn't have time to borrow it and thought it might be a touch too steep.

Chris,

I thought a lab 28 would be around a true pitch of 26. Compare this to a 27 P5X I should lose 300rpm for pitch and then another 300rpm for the extra blade. I am thinking I would only spin it around 5100. Does this sound correct?

Yes, it did settle the top end down. The boat felt stable, nose high, like there wasn't much in the water.

I just edited my post above for you.

You are correct... a 26 might be better, but a thinned and sharpened (labbed) 27 would probably be best.

See if you can try both a 26 and 27

Hydromotive will let you demo them for $50.

Not requiring as much trim is a good thing.

Your slip is down because the lower is running more parralel to the boats bottom, and the hull is carrying itself instead of needing excessive trim due to the lower unit dragging in water and leveraging the nose down. Your boat is now going thru the water like it was designed to do.

Chris

This is awesome information! Thanks for sharing! You definitly know your stuff.

So, it looks like I have got my winter shopping list. -2 Imco a cav plate and then some demo props from Hydromotive in the spring. I will let ya know what I end up with.

Thanks for adding the bit about trim, that makes sense. WIth the standard lower I would run at 6, at -2 anything over 5 I would lose speed.

Thanks,
Jon