zahndok

Can a diameter be added to a bravo 1 prop? I'm thinking if I added a little diamter and tip cupping to a 4 blade I could get my high slip down and the bow up rather than going to a 5 blade that will lift the stern. I have a 27 single step bottom v normally running a labbed B1 32. The boat seems to want more bow lift not more stern lift. Have a stock 5 blade Maximus that brought the slip down nicely but just seems like it has too much drag possibly. Thinking that if I labbed the Maximus I would cut the diameter down from stock to get the drag down, so why not just add a little diameter to the 4 blade instead. Thoughts?

articfriends

iTrader: (1)

If you fins something that works well let me know,I am also running a 30 pitch and 32 pitch labed merc prop on my boat and I'm looking for as much bow lift as possible with as little stern lift as possible. My boat (also a 27 ft single) tends to tq steer bad when you first open it up hard with the 32 labed,worse with a 32 un-labbed,Smitty

zt260

Everyone I've ever spoke to says they can do almost anything but add diameter. I think you only option is 5 blades. Call Brett at BBlades.

throttleup

Diameter can be added to a stock Bravo 1. We have done it to bring the diameter to the advertised diameter of 15.25. Most Bravo 1 props in the lower pitch range (up to about 30) are not 15.25" diameter. A stock 32-36 could be brought up to 15.5".

It is expensive, as it's very time consuming. I don't think it's the answer for what you are trying to do. As you add diameter you also add stern lift.

What are your performance numbers? WOT and speed with your current props. You may be in a situation that requires a drive spacer. There are many situations where a prop can not fix excessive slip, only lowering the drive. It's more cost effective than purchasing props and having them worked. In many instances a spacer, when needed, will increase top end as well as overall drive-ability. A spacer will also increase the bow lift.

Matt

zahndok

Thanks for the info. Single prop wot is 85 at 5300rpm. I have a labbed 32 b1 and also a labbed 30 b1 that has been pitched up a bit. Both give essentially the same numbers. I thought my local prop guy mentioned that more tip cupping (bite) would produce more bow lift. If adding to the tip length (diameter) creates stern lift rather than bow lift what would adding a little length to the trailing edge cupping do as far as bow lift? How far down in diameter can my stock 30 p maximus diameter be cut. I may try your suggestion of the drive spacer but I also don't mind experimenting with my existing props. This is a hobby ya know.

zt260

You can cut a maximus down to almost any diameter. I would not go below 15"

I guess I should have mentioned anything is possible if money is no option. I would not add diameter to a bravo though.

throttleup

Typically a Maximus is brought down to no smaller than a 15" diameter. But on certain applications they may be made smaller. Cup at or near the tips will help with bow lift, but keep in mind that a lot of cup is water resistance, which will ultimately slow you down. If you need to put a lot of cup in the tips that tells me there is usually something wrong, somewhere.

You slip is quite high. How does the boat get on plane?
Do you have to put a lot of drive trim in the boat for max speed?

Matt

zahndok

I get on plane well enough. Have to use alot of trim at top speed to keep it from porpoising. The smoother the water the worse the porpoising. Would the labbed maximus give me some of the same benefit a 1" drive spacer might add?

zt260

I would definately try a spacer first. Cutting and labbing the maximus is hard to do twice.

throttleup

A 5 blade prop is not the same thing as adding a spacer. If you have to put a lot of drive trim into the boat I bet you have a nice rooster tail.

If you are in a situation where you have to use a lot of positive trim it tells me that you are trying to push the stern of the boat down, or, lift the bow. By putting a 5 blade prop on it will lift the stern more, which will require more positive trim and possibly more speed loss and more slip.

It really sounds like you need a spacer and I think you will be very surprised how the boat performs.

Now, if you really want to give me $500 to lab finish your Maximus I would be happy to do it. I don't think you will be happy with the outcome and I think you will still need the spacer. I prefer to do the prop work at the very end. After the boat is running well and performance seems to be what we would expect to see. Then the prop work will pay off and you will feel like you are getting your money's worth.

Matt