Outboard hydrofoils?

[BassManDan]

I got to thinking since my boat is a real dog coming out of the hole and had entertained puttign one on...I rarely see these on bass boats, why?
I had one on my old basstracker and my folks skiboat had one, and they sure as hell impove holeshot and stability...so what's the drawback?

Any insight would be appreciated.

[basshogg27]

hey bassman, instead of a hydrofoil that looks silly on a bassboat, if you don't already have one throw a jackplate on the back with a holeshot plate. it goes on the bottom of the jackplate and improves on holeshot and acts as a splashguard.

[npangler]

I put one on my old basscat and it worked exellent far cheaper than replacing the prop, yes it looks stupid but if you can deal with
the commments that you will undoughtably get they work great.
I did lose some top end but not much, went from 66 mph to 61 mph. hope this helps.

[McLovin]

I had one on my Lund pro V with a 225 Yamaha and it really helped.

[big_limits]

Someone once told me if you pull out one of the rubber plugs in the prop this will help with the hole shot. What is the basis and/or truth to this if any?

[drew]

Do you mean one of the rubber isolators in the hub or the plugs in the ports near the leading edge of each blade?

If its a ported prop then removing or opening the ports will improve the holeshot. The ports work better with a relatively larger pitch prop for the application. They basically flood the prop with exhaust gases which decreases the load on the engine allowing it to increase in rpm.

At a certain prop speed the exhaust gases flowing the ports will decrease and the prop will load. At this time the engine will be further into its power band and more capable of accelerating the boat.

Someone once told me if you pull out one of the rubber plugs in the prop this will help with the hole shot. What is the basis and/or truth to this if any?

[Rod Martin]

Dan I had one on the little Mean 16 champion I had, it worked out great . On the delta I had less bow lift and was able to get on plane in shallow water better. plus when fog set in I could stay on plane at a much slower speed.

[fishinfool74]

I have one on a old 90hp merc. It was the best thing I ever did, ya people give you funny looks but hey I can still catch fish. Never lost any top end speed and stays on pad at lower speeds.

[DeltaDan]

BassManDan ... I have a unopened Stingray that is sitting in the garage collecting dust. My old boat ( an 18.5' John-style Alunimum with a Johnson 88SPL) blew just after I bought it to get help get rid of pourposing while trimmed up.


I also have a Stainless 19p Raker and a spare 19p Alunimum prop for a Johnson/Evinrude 13 spline in excelent condition.


Let me know if they can possibly help you out - come on out here and pick them up - and we will go fishing.

Cheers,
Dan

[SoCalBassAssassin]

I have one on my old 115 Yamaha. It got me on plane really quick, and keeps me on plane when moving at lower speeds. Of course my top speed on my old monark is only about 30 or so, but the stingray really helped with not only getting me on plane quicker, but I do get a better hole shot, and it seems to use a little less fuel than before the stingray. You guys can laugh at mine all you want, but on my boat it is well worth it.

[npangler]

regarding the rubber plugs in your prop, I just got my lower unit
worked on at valley prop and he sold me replacemnt plugs for
my prop and according to him its the other way around smaller holes equal better hole shot. I did this on my new basscat and
it did make a difference.

[drew]

If the outboard is fitted with a low pitch prop the vents or ports could hurt the hole shot. If fitted with a relatively high pitch prop to maximize top speed performance it will increase the loading of the engine off the line and the ports will improve the hole shot.

regarding the rubber plugs in your prop, I just got my lower unit
worked on at valley prop and he sold me replacemnt plugs for
my prop and according to him its the other way around smaller holes equal better hole shot. I did this on my new basscat and
it did make a difference.

[Oldschool]

I got to thinking since my boat is a real dog coming out of the hole and had entertained puttign one on...I rarely see these on bass boats, why?
I had one on my old basstracker and my folks skiboat had one, and they sure as hell impove holeshot and stability...so what's the drawback?

Any insight would be appreciated.

Discribe your rig; boat, engine, prop, batteries, livewells and tackle distribution and we can give your some advice that help solve the problem, instead of band aiding it.
Tom

[mark poulson]

I was told that removing one or more of the plugs from a prop allows exhaust gas to escape into the water, making it less dense, and allowing the prop to get up to speed more easily, until it bites and takes off.
I proped down from a 21 3 blade to a 19 4 blade, to let my motor run in the 4500rmp range at 35mph, which is the max. for our lakes down here. My buddy, who also has a 115 opti on his 175 Ranger, suggested it, since he said his motor wasn't happy running at 4000rpm.
I had to remove three of the four plugs to get up on plane, but it gets up fine now, and gets great mileage.

[blkdog812]

first thing i would look at is what size / pitch prop ur turning. if u have a three maybe go to a four blade or even a five. either the 4 or 5 blade will give you what you looking for.

[drew]

In general a three blade prop will have less drag and perform better for top speed. Four and five blade props are better for acceleration. The higher the blade count the better the balance which can increase the lower units service life. I agree with Oldschool about needing more facts.

first thing i would look at is what size / pitch prop ur turning. if u have a three maybe go to a four blade or even a five. either the 4 or 5 blade will give you what you looking for.

[Dom]

Great Question

I just purchased a stratos with a 175 yammie on it and it has a hydro foil. I was woundering if maybe this is why the boat only hits 55 mph it should do every bit of 65 mph, thought it might be the prop as soon as it comes back from the detail shop I will remove it then try it before I just go out and buy a prop. Thanks for the info yall


Tight Lines Dom

[BassManDan]

Good call, a little more info would help.

1997 Stratos 295 Pro Elite, 20', Johnson Venom 200hp, 25p four blade shooter SS, prop. 3 batts in the back, midship fuel tank and no tuning ports in the prop.

When I ran it out at Whiskeytown, it wasn't loaded down with all of my stuff, just a few odds and ends, but I can imagine that ~100 lbs of gear would make that much of a difference.

It has a hotfoot so I'd put my foot into it, motor trimmed way down, the bow kicks way up and it cavitates a bunch, get it up to about 3200 rpms, it starts to set on pad, I trim back up to running trim and then it runs fast and smooth.

I was thinking of swapping out for a 22p three blade, I just need to swap the hub (spline config too long).

Any insight would be appreciated.

[Oldschool]

You didn't mention a jack plate? The bow rise without coming back down quickly and blowing the prop @ mid range rpm's could indicate the engine may be set too high above the plane pad; center of the hub/prop shaft should be about 3 1/2" above the center pad, when parallel, check it with a level and straight edge.
The 4 blade prop gives you a better low end start, like a lower gear. The prop may also be modified, cupped and raked for speed/bow lift, but that shouldn't affect your set up that much.
The vented props are designed help reduce back pressure at higher rpm's, the vent holes are located to one sode of the blade cutting edge.
After checking the engine height, if that is correct, then go to a prop shop and try out a 24P, 4 blade and compare the performance. You jump up on plane and loose about 2-3 mph at the top end.
Weight should be distributed so the heavy items are behind the driver and even port to starboard. The light weight items, like tackle, clothing etc, should be in front of the driver.
Test you boat first with a 1/2 tank of gasoline, no water in the livewells for best performance. Trim the engine all the way down and make an easy 3/4 throttle start, not a punch and go start. The boat should plane easily, then trim and go. 2 cycle engines do not have a lot of torque and plane better at 3/4 throttle. Good luck.
Tom

[BassManDan]

Thanks Tom you explicit recommendations will be considered!

It might be that I need to get on the throttle a bit harder at the start, (admittedly, it was the first run so I was babying it a bit!)
As of right now the hotfoot is a bit of a reach for my leg, and I had already planned on moving it a bit closer, so that in and of itself might improve my situation considerably , having it at the optimal spot for me.

Anyway, I've got plenty of other stuff keeping me occupied till I run it again, but it will be loaded with all my gear, and at 100% ready status!

Thanks again,

[drew]

I think you have the prop venting backwards. The prop manufactures claim it will help to accelerate the boat from stop. The vents give an action that is similar to a torque converter in an automatic transmission. At slow speed there is more back pressure on the outlet of the through prop exhaust ports which forces exhaust out of the vents. Below is a claim from a popular prop manufacture.


"Vented props are available with an exhaust relief hole at the base of each blade. These holes can range from ? inch to approximately 3/8 inches in diameter. They allow exhaust gases to escape around the propeller as it begins to spin up on acceleration. The engine gains rpm more quickly and reaches its ideal power curve sooner to improve overall acceleration."

The vented props are designed help reduce back pressure at higher rpm's, the vent holes are located to one side of the blade cutting edge.

Tom

[Oldschool]

It takes some time to get used to driving each boat, they are all a little different. Once you get the set up right for you, it should handle OK.
The engine has an exhuast outlet at the powerhead that also dumps some of the cooling water overflow. This allows the engine run at idle without forcing the exhaust under water. When the boat gets up on plane, the majority of the exhaust is pushed through the prop, the vents help to relieve exhaust pressure by using the spinning prop vortex. Vents have minimal affect at low speed and the question was how to improve getting the boat on plane, I believe the boat has good excelleration.
Tom

[drew]

When the throttle is put to full position when accelerating from a stop there is a substantial increase in exhaust flow. The pressure builds greatly as it has to push the water out of the props hub. At this time it will push some of the exhaust out of the vents in front of the props blades which effectively lowers the density of the water surrounding the the prop which allows it to slip. At speed the water is rushing past the prop hub which reduces the back pressure on the through prop hub exhaust ports which effectively reduces the exhaust gas from escaping from the vents.

The vents allow one to use a larger pitch prop to obtain max top speed without over loading the engine at take off.

This allows the engine run at idle without forcing the exhaust under water. When the boat gets up on plane, the majority of the exhaust is pushed through the prop, the vents help to relieve exhaust pressure by using the spinning prop vortex. Vents have minimal affect at low speed and the question was how to improve getting the boat on plane, I believe the boat has good excelleration.
Tom

[Mitch]

I had the same problem on a 93 492 Ranger with a 225 Yamaha. I was running a 25 pitch 3-blade. I added a 6" jack plate and did not see much improvement. HOWEVER, when I went to a 23 pitch 4-blade it was like I had put a new motor on. If you have a prop shop near by, they will alow you to try different props until you find one that works the best. Goood luck and keep it WET !!!!

[BassManDan]

The vents on the motor, that make 100% sense!
That's sure something I had no idea about.

Honestly I need to run it more often and just "become on with my boat"

Thanks for all of the input fellas,