Q's about prop's

The Chipster

Cadet
Joined
Mar 3, 2005
Messages
7
I own an older Evinrude 33hp. Well I guess they are all old by now! LOL<br />Anyway, it has the factory three bladed prop on it now. I would like to know if I can put a two bladede prop on it to increase the speed a little. I am only looking for about four or five more mhp.<br />Thanks for any help on this one.
 

Paul Moir

Admiral
Joined
Nov 5, 2002
Messages
6,847
Re: Q's about prop's

Welcome to Iboats, Chipster!<br /><br />Old Michegan Wheel 2 bladed props pop up from time to time on ebay (I only see one for a V-4 and another for 22.0CID blocks now). I belive they're all bronze props which will be very hard on your gearcase. Not really reccomended unless you're racing.<br /><br />On the other hand, there's a lot you can do with your engine with setup. You can raise the engine up quite a bit (make sure you are still pumping water at idle & full throttle) which will raise your R's and speed by improving efficiency. You may have to set up your boat to use the bolts rather than the clamps if you get up high enough.<br /><br />If you don't have one already, you'll need a tach. A good, inexpensive tach that will work on your magneto is the 'tiny tach' from www.tinytach.com<br />Without having that information, you're really flying blind.<br /><br />Finally, make sure you have your engine in top shape. If it hasn't been done recently, do a thorough decarb. The piston rings sometimes get stuck in the pistons from carbon, and you can often improve compression by freeing them.<br /><br />What prop have you got on it now? I mean what pitch prop? It may have a number on one of it's blades, or in the hub area under the thrust washer.
 

LubeDude

Admiral
Joined
Oct 8, 2003
Messages
6,945
Re: Q's about prop's

Hello Chipster and fellow ORYGONIAN:<br /><br />Paul is such a nice guy :D and I might say, Very knowledgable too. <br /><br />Now with all my Awesome tact Ill tell you what I think.<br /><br />First off gaining 4-5 MPH with just a 35 HP engine regardless of prop and setup, depending what type of boat it is on is really asking for something. Not completly unheard of though. Let us know what type boat, where the cavitaion plate is in refference to the bottom of the boat and the RPM #s when you get a tach, and we will see what we can do.
 

The Chipster

Cadet
Joined
Mar 3, 2005
Messages
7
Re: Q's about prop's

Thanks for the info. Sounds like I should just find myself a larger engine. My boat is a 1964 or so Seaswirl 14'. With a 33 Hp. I think I'll look around for a 40 hp or less.
 

Paul Moir

Admiral
Joined
Nov 5, 2002
Messages
6,847
Re: Q's about prop's

I think I'm closer to Germany. :D <br />Nova Scotia is the peninsula on the eastern cost of Canada, so no.<br />Try raising that engine up; the more of that gearcase you can get out of the water, the less drag you'll have. And it's not like that lower unit is exactly the picture of hydrodynamics at their finest. <br />The 33hp is a little underrated. It's essentially the same engine as the earlier 35hp engines with some internal improvements, a better l/u, etc. The 40 is a larger engine though (43.9 vs 40.5 cubes) and I belive will directly bolt on to your 33hp leg. :)
 

The Chipster

Cadet
Joined
Mar 3, 2005
Messages
7
Re: Q's about prop's

Thanks again for the info. There is a outboard salvage yard a few blocks from my home. I'll go there and check into changing the lower end. You never know, you know. LOL <br />The photo on your message looks exactly like an area on the Willamette River betwwen Oregon City and Portland.
 

daveswaves

Ensign
Joined
Mar 22, 2002
Messages
901
Re: Q's about prop's

My 2 cent's, I run a similar setup to yours with a 1964 14 foot fibreglass hull, 1964 Evinrude 40HP Lark V. If it is the original prop on it you will probably find its just under 14 pitch, 13.25 I believe.. I sent mine to a prop shop and had it retuned to 14P. I had originally planned to raise my motor up as Paul ahs mentioned. I have the electric shift lower end so it is very streamlined and pointy. I have a 35 hp maual shift as well with the "BLUNT" end that you have so I know what Paul is referring to. I originally put the cavitation plate level with the bottom of the hull but I had extreme cavitation in turns or rough water. I ended up moving it down untill I could grab all the time, but only just. My point here is that your hull may be limiting you, not the prop or depth. I run 25 to 26 MPH at 4200 RPM which for me is WOT, My problem is the hull which <br />wets" out too much. There is a hook in the bottom of my hull near the stern that is forcing the bow and the centre line to run "in the water too much. This is very common in old fibreglass boats, especially if they have sat on a trailer for a long time. Come spring I will repair the hook and hopefully gain rpm and speed. Just something to check.
 

The Chipster

Cadet
Joined
Mar 3, 2005
Messages
7
Re: Q's about prop's

OKAY PAUL! Looks like we got the same thing goin on!LOL<br />I just got given a 35' Criscraft. I think I will work on that one for a while. I guess I am stuck with what I got. LOL
 
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