Sluggish Holeshot

[Gary Fish]

Hello all..



Last year, we bought a 640lx with a 60hp four stroke. When we were considering our options, speed was not the priority. Instead, we were looking for a light weight boat that was easy to load and maneauver. Our priorities have not changed and we love our boat!



The problem...with the low torque of a four stroke engine, it takes forever to plane out. We tried changing the prop from a 13 pitch to an 11 pitch. With the 11 pitch, it planes out nicely but our speed has dropped from 35 to 25 mph. Okay...speed is not my priority, but this is a pretty big sacrifice for a better holeshot.



In my other life, I am a private pilot. In the world of aviation, achieving the correct "weight and balance" is essential. Has anyone tried adding weight to the front end of the boat to improve the balance??? It looks like I could easily add a couple of 25 lb. balasts (lead shot in a bag) in the front end of the storage boxes. Is there a drawback to this approach other than limiting the total amout of weight I can carry? Will it improve the holeshot?



The other option I am considering is adding a hydrofoil. Any success stories with these???



Appreciate any constructive comments you may have.



Thanks,



gfish

 

[Bryan McDonough]

Hydrofoil is a good option here.

 

[Greg Meyer]

Gotta go with the "dolefin" or hydrofoil...

 

[Marty Klein]

I think the 60 HP is anemic for the 640. I'm not sure what you're expecting for a hole shot. However, once the hole shot is over, why would you want to carry an extra 50 pounds of lead around?

 

[Gary Fish]

Thanks for the comments.



The last time out, I ran the 11 pitch prop. It would easily redline @ 6,000 rpms if I allowed it to do so. With the 11 pitch prop, it takes around 4-5 seconds to plane with a top end around 25 mph. With the 13 pitch prop, it takes 10-12 seconds to plane with a top end around 35 mph.



I don't particularly wish to carry around an extra 50 pounds. But if it works, so be it. Ironically, my Piper Cherokee 140 flys considerably faster (+10 mph) with an extra 50 pounds in the back seat!!! Most of these airplanes were rigged nose heavy from the factory. Again, it's that weight and balance thing.



Does anyone have experience adding weight to the front end???



Thanks again,



gfish

 

[Gary Fish]

Hello Dave...



Good idea. It is a 12 volt trolling motor.



I considered moving the batteries up front but I'm not sure where I would put them. With my original lead weight idea, I could slide the balast(s) all the way up to the front of the right and left storage compartments (where they actually meet). Naturally, I would need access to the batteries. The only way to do this would be to cut a panel in the front deck forward of the pedistal. Don't think I want to do that!!!



Thanks for the input.



gfish

 

[Stan Tallant]

You wouldn't need to cut a hole. Just screw in a battery tray with a snap/strap in the front of the boat inside the huge compartment (in the center) under the seatpost area. That way you can charge it easily from either side and unsnap it to add water and you still have room for your rods and life jackets.

 

[Gary Fish]

Thanks for the advice Pat...any recommendations on a prop doc?

 

[Bruce Freeman]

Gfish, balance is an issue but adding weight is not the cure. The right prop and the right set up will help the most. You can fine tune by moving the weight around in your boat once you get the right set up. Read Pat's post again, "Find/get a good stainless 12 with large vent holes, and your holeshot will improve, and your top speed will return.

Four strokes need the venting to help spool up the rpms to develop what enimic power they have. Your current prop probably doesn't have vents, and you're starting out in third gear going up hill." Find a prop shop that will loan you a prop and find what works for you.



BF

 

[Gary Fish]

Thanks Bruce.



I am, indeed, pursuing the 12 pitch stainless prop. On Mercury's website, their "prop selector" recommended their four blade Trophy Sport stainless prop at a price of $367. On the other side of the price spectrum, I am looking at an Apollo Stainless-Michigan Wheel three blade prop for $173. Any thoughts on either of these options?



Thanks again.