New prop and/or hydrofoil???

[jstaz]

I have a 60 hp tohatsu on my 17' boat. I have GPSed the top speed at about 30 MPH. I am ok with that speed, wouldn't mind getting more out of it though. However, I would like to get on plane faster. It seems like it takes forever to plane out.

Would a different prop work better? Adding a hydrofoil? or both? work best to get on plane faster and maybe get a little more speed out of my motor?

If a hydrofoil is where it's at... What is the best brand? Does it matter?


Thanks for your input.

 

[Bob_VT]

Re: New prop and/or hydrofoil???

We have had "mixed" results with hydrofoils and first you might want to check your loading, engine set-up and trim.

If you need a hydrofoil....iboats sells them.

 

[JustJason]

Re: New prop and/or hydrofoil???

If your looking at hydrofoils, look into smart tabs as well.

 

[steelespike]

Re: New prop and/or hydrofoil???

I feel a foil is a bandaid over a design/setup problem.
The antivent plate (just above the prop)should be about even with the bottom of the boat.Visable on plane.We need to know your prop size,on the barrel or under the prop nut. Need your wot rpm. Need year of motor,2 or 4 stroke.Boat brand, model and al or glass?
In the extreme raising the motor could slightly improve hole shot and increase speed.Wreight distribution is important if there are 2 or more batteries in the stern
moving them forward would help.Move passengers forward till you plane.Be sure to trim down all the way for hole shot.
Depending on your present specs a prop change might improve hole shot and speed though they seldom go together.Get us your specs and we'll go from there.

 

[QC]

Re: New prop and/or hydrofoil???

If your looking at hydrofoils, look into smart tabs as well.

I would say instead . . .

 

[rallyart]

Re: New prop and/or hydrofoil???

A hydrofoil is the least expensive, quickest to install, and most effective way to eliminate bow rise. I have used and recommended the Stingray brand. Others may be as good. Trim tabs can help and adjustable ones have added benefits. Props won't make much difference in the bow rise but they can reduce the time the bow is up.
There are disadvantages to adding a foil. Your steering is likely to feel stiffer, especially at higher speeds. You may need to adjust the steering trim. They may hurt top speed and will create more spray at the transom.
If you are out in a storm you can run slower, safer because your bow is lower at slower speeds. They are worth looking at and if you don't like it you might have wasted $50.

 

[QC]

Re: New prop and/or hydrofoil???

Smart Tabs do all that ^^^^^ for $100 and there is no potential for serious safety side effects.

 

[rallyart]

Re: New prop and/or hydrofoil???

I've never seen any 'serious side affect' but I'd be open to find out what they might be. Smart tabs are OK and less money than adjustable tabs. By your numbers they're twice as expensive and they definitely don't stop bow rise as much as a foil can. The foil does not affect reversing as much as Smart Tabs.
It is all a matter of choice.

 

[dockwrecker]

Re: New prop and/or hydrofoil???

Smart tabs are infinitely better than foils. No chine walking, steering issues, etc. Foils are a poor band-aid. Fix it right and be happy, the money isn't that much.

 

[QC]

Re: New prop and/or hydrofoil???

There are no backing issues with tabs either, and they help with wander at displacement speeds. There are many, many reports of dangerous heeling and trim issues with foils . . . I'd like to see bowrise angle and time to plane comparisons.

 

[JimS123]

Re: New prop and/or hydrofoil???

Lots of opinions out there and most of them are wrong. Just so much bad info, it makes my mind boggle....LOL. Nobody yet has asked the right question(s).

Look at your owner's manual to see what the proper operating rpm of your motor is. Let's say for example it is 5000-5500 rpm. If your motor does not run 5500 at WOT, then you need to change the pitch of your prop so you obtain that number.

If you are currently meeting the specified max. rpm and still not planing fast enough to suit you, then you have 2 options. You can spend $100 and drill 12 holes in your transom and install trim tabs, and get improved performance, or you can spend $39 and drill 4 holes in your motor, install a Doel Fin Hydrofoil and do the same thing. BTW, these holes won't rot or rust and when you sell the boat nobody will even be the wiser.

Big heavy boats with heavy engines profit from tabs, and in many cases they are std. equipment. Little boats like yours don't perform well out of the box because boat hull design ain't what it used to be (IMHO). That's why they need an improvement.

Many people cite negative effects of foils. I've never seen that personally. All positives with no negatives. 5 boats in my family and 4 have fins. 2 I/Os and 2 OBs. The 5th is 58 years old and doesn't need them.

At worst it won't work and you can sell the $39 part on Craigslist for $25.

 

[omcgreasemonkey]

Re: New prop and/or hydrofoil???

foils tabs who knows but ive found foils to add drag and make the boat more difficult to trimout as a tech i advise my clients to trimtabs and heres my statistics mmi grad year 2000 worked on numerous boats owned 7 boats only my mako had trimtabs for the flats others if they had foils they got removed i wanna trim out and be up on the water not stuck with my nose barried

 

[N3UP]

Re: New prop and/or hydrofoil???

I had a Stingray on my 73 MFG Gypsy using a Merc 650.

That motor didn't have power TnT so triming while underway was not an option.

Once I got the pin set correctly (it was one hole further out after the fin was installed) I was able to get on plane faster and stay there at a lower speed.

It did everything I expected of it.....

That said, my motor was also properly propped for the application.

 

[DaNinja]

Re: New prop and/or hydrofoil???

I may have to keep up with these threads. I was thinking about tabs and a foil for both boats.

 

[jstaz]

Re: New prop and/or hydrofoil???

1994 17' TD Penny v-hull (center console layout but with two consoles) fiberglass construction

1994 Tohatsu 60 HP WOT 4900-5600 RPM 2 stroke

Prop... I don't know the diameter and the pitch for sure. Can't find it on the prop possibly because of corrosion being where it could have been. Owner's manual states that 13 pitch is the standard from factory on this model of motor. It is an aluminum prop. I believe everything is stock because the other 2 owners did not change anything on the boat from the knowledge I have.

WOT on the boat is currently 5200 RPM

 

[JimS123]

Re: New prop and/or hydrofoil???

You want to hit 5600 rpm. If you do, its likely that you will solve your problem with no other add-ons needed. To achieve that you need to go up about 2" in pitch.

Take your prop to a prop shop and have it measured, then go from there.

 

[QC]

Re: New prop and/or hydrofoil???

You want to hit 5600 rpm. If you do, its likely that you will solve your problem with no other add-ons needed. To achieve that you need to go up about 2" in pitch.

He needs to go down in pitch to gain 400 RPM . . .

 

[JimS123]

Re: New prop and/or hydrofoil???

He needs to go down in pitch to gain 400 RPM . . .

Duh.....LOL. It's a rainy Sunday and can't take the boat out. My thinking and typing are askew.