87MagnumII

Had the boat out today. Seemed to run good considering outside temp was around 80-82 degrees.

Boat is a 1987 20' concord, mildly built SBC power alpha drive, 21 pitch laser II.

When planing I noticed if I gave it to much stick it wanted to blow the prop out a good bit, it came up pretty quick but definitely was blowing out

Cruise speed was good and handled great

Top speed was 61.5 @ 5200 rpm
Depending on the drive ratio, either 1.5 or 1.47, I don't know which it is, puts the slip at 11%-13%.

I'm going to run again tomorrow and switch the prop up. I have a 23 laser II and a 21 mirage (non plus) to try as well What prop do you guys recommend for more top end and a little more bite on the bottom side? I'm going to send one of these three props in for work once I figure out which one the boat likes but was hoping for professional input.

I just feel like this boat is capable of 65 mph but I may be wrong

The extent of my prop expertise is being able to count the blades

bbladesprops

Hi Dave sorry for the long delay in responding.

There are some thoughts I have concerning your rig. There are actually a number of Concords in our neck of the woods. Great lines on those boats.

Three blade props are what you will want to stick with on your hull for the best top speed. Since your slip % is good on the top, we will need to find a way to spin larger pitch props at higher rpm levels.
Let me know how the Mirage and 23 Laser 2 propellers worked for you. Also, we need to know your desired rpm level at WOT for your engine.

If it is convenient to call us I can give you my thoughts over the phone.

Thanks,
Brett

87MagnumII

Brett,

Had a few minor issues with the boat and have not been able to test props just yet. I will be running everything I have tomorrow and will post back with results.

I will say the 21 laser needs a bunch of trim. I'm hoping that maybe the 21 mirage (non plus) won't need as much to get the boat up on top.

Any thoughts would be great from anybody else that reads this.

87MagnumII

Ran the mirage 21 today. 61 mph gps at 4800 rpm. 1.5 ratio drive
Is it possible to get to 5200 and keep the slip around 6%? I'd love to get 65mph out of it

bbladesprops

Knowing your boat, the fact that those boats love bow lift and the fact that you are running so efficiant now
as well as you having a Mirage not a M PLus, I feel more confident on a 1 or 2 mph gain rather than 4 mph. Also the rpm gain will most likely be low as well. Getting a bunch of rpm would require depitching and that will not increase speed.

Brett

87MagnumII

I'm going to try a 23 laser this coming weekend and see what kind of numbers it gives. Which prop would be better for bow lift, the mirage or laser series?

bbladesprops

The Laser 2 up to 22-24 feet in stock condition. The Mirage after that. The Mirage can be customized more though due to its larger canvas to work with.

Brett

87MagnumII

Brett,

what about a Mercury Enertia?? from the description on their web site it appears to be a blend of the laser and the mirage. also says it has thinner blades and a high rake for top speed gains? do you think it would be worth a shot?

bbladesprops

Absolutly, test every prop you can.

B

87MagnumII

Called today and talked to Brad. He said u should have the enertia back in stock today or tomorrow. I'm gonna test it when he calls and let's me know it's in