ferraristyle

I have a 1987 21' Scarab I, Merc 260 engine, Alpha sterndrive. To the best of my knowledge, it's the stock prop that came with the boat; 3 blade RH. I'm not at home right now so I don't have the numbers on the prop.

Looking for the best, top end, speed/crusing prop. I usually have about 3-4 adults in the boat, and don't do much sking/towing so I was even thinking about going to a 2-blade set up.

I just want to be able to run fast. I know props are sort of a mystery, but I'm thinking I should be getting more then 45-50mph out of this boat. I had an aftermarket "whale tail" on the sterndrive that I've been told to remove because it's costing me performance. I'm also going to get an alignment done, just to be sure.

Mechanics of engine and drive all check out.

Any help and place to purchase would be great. Will purchase ASAP as soon as I know what to get.

throttleup

If you could post your performance numbers, please.

What is your WOT RPM?
WOT MPH via GPS only?
Gear Ratio?
Prop pitch and make?

With a little information I will try to assist you.

Julie

ferraristyle

Ok, Here's the info I can get you.

The boat is an '87 21' Scarab I.

I don't know the gearing. I'm going to assume what was normal for a Merc 260 Alpha Drive combo but can't be 100%.

At WOT I'm running 5K RPM's. Top speed trimed out I have reached was 44 MPH via speedo; I don't have a GPS reading. That was with a load of 3 adults and two kids. 1/2 tank of gas. I also had a large "whale tail" fin on the back that I'm sure wasn't helping matters much (took that off tonight)

The prop that is on it is a Quicksilver 48. It also had the numbers 16316 45 19P on it. In relatively good shape. I also believe it is stainless steel. RH motion.

Hope this info will help. Thanks in advance

ferraristyle

Throttle Up or BBlades or any prop vendor as a matter of fact can you guys help me out with this?

throttleup

Well it is very difficult to assist you without knowing your gear ratio and speed via GPS. We can take an educated guess on your gear ratio but the GPS rarely lies! This information is used in several calculations to determine your efficiency. The part number you posted is a Vengence propeller made by Mercury. I can tell you that the operating range for your motor is 4400 - 4800 RPM at WOT. So you are over revving your motor at 5000 RPM at WOT. I would recommend that you stay in the 3B design and try a Mirage Plus 19P. It has a little larger diameter and will runn a little lower RPM for you.

Julie