Help me make my Glen L Stiletto Wooden boat FASTER!! (Advice needed)

[blacktruck]

I think just raising the motor to optimum height, which will probably be just 2 or 3 inches hire than the plate lined up with the bottom will make it a little faster and improve handling. When a lower unit is too low it drags through the water and can cause handling issues.

Personally, I think you're running that boat in the sweet spot. You can mod the engine, but the hull is limited and it would take too much modding to get it close to 70's. The hull is not really designed for those speeds. I'd say play with the engine height, props etc. Have a safe handling, respectable performance boat that's economical. If you want to go 70 plus someday, invest in a hull designed for that kind of performance. Just my 2 cents.

Thanks! I will measure as you mentioned tomorrow.

I was wanting a goal of mid 60's with a dream of close to 70... Is this impossible with this type of hull? Or just impossible with that motor?

Future Mods I was thinking about were as follows:

Jack Plate
Prop Change if needed
Trim Tab move (if needed)
Milled Head (higher compression=more power)
Boyeson Reeds

I know the fastest way to have a faster boat is to buy a faster boat.... I just like the classic looks of this boat and love the compliments every time it is on the water. I want to also impress with its performance.

Let me know if these goals are unrealistic... I could always looks for a larger engine, but it would be nice to make do with what I have.

[80's old school]

I think just raising the motor to optimum height, which will probably be just 2 or 3 inches hire than the plate lined up with the bottom will make it a little faster and improve handling. When a lower unit is too low it drags through the water and can cause handling issues.

Personally, I think you're running that boat in the sweet spot. You can mod the engine, but the hull is limited and it would take too much modding to get it close to 70's. The hull is not really designed for those speeds. I'd say play with the engine height, props etc. Have a safe handling, respectable performance boat that's economical. If you want to go 70 plus someday, invest in a hull designed for that kind of performance. Just my 2 cents.

I will start with this first. I need to install my water pressure gage first. Then I will raise the motor incrementally. Since it is in the lowest position now... I have 3 more positions to raise.

Since I don't have a jack plate, I will take my engine hoist to the lake. I can make adjustments...run the boat and evaluate and then make adjustments again..


I appreciate everyone's advice. I just want to tune to the sweet spot to make this rig run the best she can... maybe 60 MPH is a more realistic expectation / goal!!

[blacktruck]

Ya, you got it. This will help with porpoising too, with the motor raised, you can run it flatter while reducing drag. You really don't need much trim on a flat hull like that. Good luck.

I will start with this first. I need to install my water pressure gage first. Then I will raise the motor incrementally. Since it is in the lowest position now... I have 3 more positions to raise.

Since I don't have a jack plate, I will take my engine hoist to the lake. I can make adjustments...run the boat and evaluate and then make adjustments again..


I appreciate everyone's advice. I just want to tune to the sweet spot to make this rig run the best she can... maybe 60 MPH is a more realistic expectation / goal!!

[olboatman]

I would say to get 60 mph out of that hull with 115 hp is doing very well. Gary

[Go Time]

We built one of those in the early 70s. Without a keel or skeg the boat was very sktchy when turning. It also help stability when operating at wot. I recommend keel/pad ....the skeg in the midship could cause the boat to hook when turned real sharp.

[Jimboat]

...guessing / estimating the centerline of the propshaft is about 5-6 inches below the bottom of the boat with the engine being level.

Raising the motor will definitely give you more speed, as your current setting stated seems pretty low (so, a lot of unnecessary drag). You should get a several more mph by raising height. You should get be getting good water pressure even raising your motor since you're well buried in the water now, but a water pressure gage is always the best insurance.

The boat gets faster and faster the more you trim, but the porposing gets to be too much.

This hull is susceptible to porpoising, probably see it starting at ~40mph right through to 60mph. Flat bottom is more susceptible to onset of porpoising. Changing engine height may also improve porpoising issue. [see article on Porpoising]

...could some form of pad be built to the bottom and faired in?

Flat bottom won't benefit from a pad, since flat running surface is already very efficient.

[Bodhi]

In addition to all the good advice above.....possibly just raising the engine and switching to a big ear chopper prop will help. Choppers will add some bow lift to this boat and throw more water than an omc thru hub

[80's old school]

Jimboat, thanks for the input. The more I read the more I learn. I will be heading up to the Lake House today to get actual numbers on the requested motor height, checking for hook in bottom of boat, etc.

Thanks to everyone contributing. This is a very engaging forum... the more I read, the more I learn.

[80's old school]

In addition to all the good advice above.....possibly just raising the engine and switching to a big ear chopper prop will help. Choppers will add some bow lift to this boat and throw more water than an omc thru hub

I was wondering about Chopper Props.. If advantages are faster speed...what are the disadvantages?

[80's old school]

Does anyone know what the rev limiter is on my 1997 Evinrude 115 60 degree Eagle motor?

Also, is the rev limiter a hard rev limiter where you know it hits because it abruptly shuts down speed, or is it a soft limiter where it simply drops some cylinders where it smoothly settles at the rev limit?

Also for short bursts, what is the max RPM this motor is good for? I premix with Evinrude XD100, so I feel I am putting my "best foot forward" with lubrication.

[Bodhi]

I was wondering about Chopper Props.. If advantages are faster speed...what are the disadvantages?

No disadvantages really, they are specific for they're purpose. ..bow lift. There are many styles to the chopper , one being a small ear which will spin higher rpm with a bit less bow lift. I personally like big ear choppers for flying the bow high. Cleavers on the other hand will give stern lift . But anyone will tell you, you'll go through a few props before you find that "sweet" one. Took me 4 props to find my cleaver that flys me just right

[80's old school]

Measured a few things today as requested.

1. Propshaft centerline is 8.75" below bottom of boat.
2. Cavitation plate is 1" below bottom of boat.
3. Bottom measures flat. No hook noted. No flaws or issues noted on hull.
4. Trim Tabs are mounted flush to bottom of boat.

Looks like a jackplate plate will be needed. I only can move up the engine another 2". That will still put me at 6.75" prop centerline below bottom of boat.

[TooStroked]

Based on your measurements, I'd say you can move the motor up quite a bit - assuming you still have adequate water pressure. Moving the motor back with a Jack Plate will help even more since you'll gain leverage to lift the bow. With a stock 115 on her, I'd be quite happy with around 60 MPH.

As for the Trim Tabs, as others have said, they're probably there to address the porpoise issue you're still seeing some of. Moving them up so that they're not parallel with the bottom will reduce drag. Generally speaking, you want to be up the transom at least 1/4".

One final thought. Moving all of the stuff around on that beautiful transom will involve removing and re-installing fasteners. Make sure you carefully / fully re-seal the holes when you put anything back in place. I'd hate to see you ruin that beautiful boat by getting water into the transom structure and rotting it out.

[Jimboat]

Measured a few things today as requested.
1. Propshaft centerline is 8.75" below bottom of boat. 2. Cavitation plate is 1" below bottom of boat. 3. Bottom measures flat. No hook noted. No flaws or issues noted on hull. 4. Trim Tabs are mounted flush to bottom of boat. Looks like a jackplate plate will be needed. I only can move up the engine another 2". That will still put me at 6.75" prop centerline below bottom of boat.

At the height you've measured, the height of your motor is certainly affecting your top speed, acceleration and handling. There is too much lower unit in the water, creating a lot of drag. The important measure is the location of the lower unit 'torpedo' (prop shaft), not necessarily where the cavitation plate is located, but if your lower unit height is sufficiently low that the cavitation plate is actually wetted, then this is creating a huge amount of unnecessary drag. Raising your engine will help your top speed significantly and will also reduce the 'bow-down' moment currently causing significant hull bottom wetting (and drag). The location of your Dynamic CG will also be altered somewhat by raising your engine, which will change the susceptibility to porpoising. If your engine is a long shaft model, this could be the height issue, short shaft engine is intended for this boat. You might be able to simply build up your transom if you don't wish to go to the expense of a jack plate. You can also expect that your prop selection can change somewhat with the change in engine height.

[80's old school]

Here are some pictures I took today.. They show how low the motor really is and how the Trim Tabs are flush to the bottom of the boat.



Work is needed!!!