Hydrofoil

[Bill Kowalski]

I have 97 Rajun Cajun with a 150 edi that has a planing issue.  I changed the prop which has helped, but still experience trouble planing out.  Thinking of a hydrofoil.   Any suggestions?

[skunked_again]

Do you have a jack plate?

[Bill Kowalski]

Yes, a manual one.  Previous owner said he had it set optimal.  Lifting it would be a b*tch 

[Catt]

Nautilus Smart Trim Tabs 

[Way2slow]

A hydrofoil will help any of them get on plane.

 

Since you didn't give much info, it would be hard to help.  Boat size, HP rating, type motor would help.  Unless it's a 20' boat, there are probably other issues going on that's causing your problem.   An 18' boat should pop out of the water with a 150, a 19 can be a little slow with the wrong prop and a 20' can be down right sluggish with the wrong prop and weight distribution.

 

Some issues can be:

motor performance problems

Weight distribution.

Under powered hull

Hull problems like water logged flotation foam.

Poor setup in general.

 

 

 

[Bulletman20XD]

If the planning issue is new, it could be that the boat is now loaded differently than before or something is going on with the motor that needs to be checked out by a shop. A planner will help any boat plane faster as has already been mentioned but simply adding one will not fix a problem that may exist. Also not know what motor--prop etc... Some merc/custom props can be tuned with mercury's PVS plugs. Made a mountain of difference with one of my props!

[WRB]

You changed the prop from to? Boat length? It's not too difficult to change a manual Jack plate setting, don't want to raise it if you have a hole shot issue, you want to lower it 1/4" to 1/2".

Tom

[Bill Kowalski]

Boat length is 18.5.  I changed props from a 24p to a 19p, which helped, but still lags.  I figured a hydrofoil would do it.  Faster and cheaper than taking it to a shop was my thinking.  

[WRB]

1 hour ago, Bill Kowalski said:

Boat length is 18.5.  I changed props from a 24p to a 19p, which helped, but still lags.  I figured a hydrofoil would do it.  Faster and cheaper than taking it to a shop was my thinking.  

24 P 3 blade SST to 19 P 3 blade SST, your rpm's must be way to high with 150 hp on a 18.5 Cajon. If your OB can't swing a 19 P over 5,800 rpm's it's a sick engine.

I was going to suggest a 22 to 23 P 4 blade to get you out of the hole quickly but you have power issues or a wet hull.

Tom

[Way2slow]

I agree, a 22 or 23 inch is what I would think that boat should turn.  I would suggest taking a serious look at the motor, starting with a leak down test or find someone that has a good dino and knows how to use it and check the hp.  The thing about a 6 cylinder two stroke, the can be down a cylinder and a lot of people can't tell. 

[fishnkamp]

There is several things to think about.  Is this a "new to you" used boat?

Has this boat ever gotten up on plane or did something in its performance change?

 

If this is a boat that you have no idea how it ran before or something has changed then I am going to suggest checking some quick easy stuff first.  Have you checked to see you are getting full throttle. Take the engine cover off and get someone to help you. Have them work your throttle and see if you are getting full throttle. The cable should mover the linkage till it hits the stops.  Old throttle cables can easily stretch out and not work.  If this is the problem the solution is new cables. Also if it has a hot foot this is a common problem and that often takes just a readjustment.  If your boat is reaching full throttle the next thing I would do is to replace spark plugs, fuel filters, start with dumping your fuel and getting fresh fuel, and replace the fuel lines. Always add a fuel treatment like Star Tron.  

These are standard things to do on an older motor.  Fuel lines have also been a big problem due to their reacting to the new ethanol fuels. The internal linings of the lines can deteriorate and clog or balloon up and restrict fuel flow. If these have not been changed I would just replace them all with the new Ethanol approved lines. They are available in bulk from your local boat dealer.

A compression test on all cylinders is warranted too. 

 

If you handle all of these items then test run your boat. Be careful because if this work fixes the problem than the smaller pitch prop may cause your engine to try and over rev. Pay attention to your tach and also jot down the top rpm and speed to see where you are after these things are done. These steps won't fix any electrical issues you may be having on the engine like a failed coil pack, but if you fix the list I gave you and there is a still an issue than your mechanic will have less to test saving you money.

[Bill Kowalski]

Ok, thanks for all the great advise.  I'll check it out first before going to the foil.

[Bill Kowalski]

One more question.   RMPs weren't an issue as I made sure once changing and saw better performance.  So now I'm leaning to more motor performance or other issues as posted.  My question is what is the performance difference with a 3 blade to the 4 in same pitch?  Better hole shot with the 3, but over all speed with the 4 blade?

[WRB]

A 4 blade prop is like a lower gear ratio, more power at lower rpm's and will get up on plane faster. You will sacrifice top end speed with a 4 blade vs a 3 blade by a few mph. If your engine doesn't over rev with the 19 P prop, you have a power problem that a 4 blade prop can't remedy IMO.

Tom

[Bill Kowalski]

I agree with you Tom.  I have a power issue.  I will pursue this angle. 

 

Thanks for the help!

[Bulletman20XD]

I wouldn't worry about props at this point. You changed from 24 to a 19 and its still bogging down--There IS something wrong with your motor. With that 19, it should either jump up on plane or the prop would cavitate so bad you'd know by the RPM increase!! This is an EXPENSIVE outboard and never should you try and fix a problem by going cheap when in the long run it could cost you thousands!

 

Been there done that!