More bite

[ddaigle]

I have a 1989 70 hp evinrude pushing a 17 ft bayhawk -very small tunnel, basicly a flat bottom. I am running a 15 pitch rapture 3 blade and have smart tabs. Due to fishing in extreme shallow water I run this motor with the propshaft about even with the bottom of the hull. I have a remote water pickup so cooling is not a problem. Hole shot is awesome when it bites and I can trim the prop higher than the bottom of the boat at speed without losing bite. However, I want to raise the motor higher for getting on plane in shallower water. I added some cup to this prop, but I guess my question is would a 4 or 5 blade be a lot better or can I make the 3 blade work? Thanks

 

[steelespike]

Re: More bite

There are surface piercing props I don't know if they would work for your purposes but someone will be along with more info.

 

[ddaigle]

Re: More bite

Thanks steelespike, I know about the surface piercing props, mine is actually functioning as one as I can trim it higher than the bottom of the boat on plane. What I need is more bite on takeoff in very shallow water. I am on the ragged edge with the 3 blade but I dont want to spend almost 400 bucks on a supercupped 4 blade and not get much improvement. I know some of the prop guys on here may know something.

 

[Texasmark]

Re: More bite

Trim tabs help lift your arse and with them you can plane out faster/ at a lower speed....because you have a water deflector mechanism farther aft. Around the Texas coast, tunnel boats that run the bays and brackish water (sometimes inches deep) are like that too......the engine is mounted forward of the aft of the boat and that extra boat farther aft than the prop helps to get the bow down fast. Then for top end just tuck them up. Might look into that.

Mark

 

[ddaigle]

Re: More bite

Thanks Mark, I have smart tabs right now. I live on the Texas coast in tunnel boat country. I just dont have the money for a tunnel boat. I have managed to turn my old bayhawk semi v tiny little tunnel into a boat that can run in 4 inches of water and take off in 14. With the smart tabs and the engine tucked I can almost drive the front end under water. Absolutely no bow lift. My problem is I need to take off in less than 14 inches to get to a lot of the laguna madre. To do this I need to raise my motor even higher than the extreme height I have it at already. I am just wondering if a 4 or 5 blade prop will give me enough more bite than my 3 blade to make the cost worthwhile.

 

[Texasmark]

Re: More bite

I'm going to say yes and SS is a must. You will be cutting part of the bottom on every hole shot so as you are aware, you want to pogo-stick out of the hole and your prop will have to tolerate the debris; course the nice thing is, unless you are on top of an oyster reef, is that the material that the prop blows out is movable, not like smacking a rock which could damage your lower unit.

Only thing I will add to that is that your pitch is such that your engine can develop it's hp rapidly......course that's where prop porting helps.....it allows the prop to ventilate on hole shot which unloads the engine, allowing it to "race" and in doing so your punch out is much faster.

I would think that the right prop and pitch for that function would be pretty lacking on top end, but that's the price you pay.

Course, that's why I like ported props. You get ventilation for rapid acceleration in the hole and then when you are up and running, the holes close and you realize the gain if your higher pitch that you can tolerate with the holes.

Sure miss that kind of fishing.....and eating the "spoils of war". Grin

Good luck.

Mark

 

[steelespike]

This is a 7 year old thread. You should get a lot more help if you start your own thread. there is a tab at the top of main prop forum page.
Is your speed by gps? You might add some cup And a 4 or 5 blade may help.Sounds like your allready too high.
Maybe a powered jack plate.If your likely to hit bottom I would hate to see what it would cost to fix a 5 blade.