Speedmaster Sport 20 hydro strut

[Norwest]

Use liner and bend is too gentle coming out of hull!

[properchopper]

Use liner and bend is too gentle coming out of hull!

I've experienced this situation before. I arrived at this exact conclusion FWIW.

[IRON-PAWW]

Ok. I wondered if the gentle bend might have something to do with it. So. I need to throw away the 1/4 tube and get the size that will take a liner? Re-doing the bend with this 1/4 tube and no liner isn't going to work? Can someone show me a photo of the curve I need? Cheers muchly. Think my RC Boatbuild FE30 uses no liner :-)

[properchopper]

I believe that there's a certain stuffing tube/shaft bend angle that, when exceeded cancels out the harmonics. I've been on both sides of the issue. The bend I put on FE30's seems to be on the happy side, and being teflon-less seems to be the hardcore race setup (although I'm willing to side with Mark on this). Teflon surely won't be hindering full P setups but my thinking is that for P-Ltd Power even a teensy bit of (probably imagined) greasy teflon induced parasitic drag could knock off a few needed RPM's.

pictures will follow

This is a bit noisy with a smooth, gradual curve:

shaft some noise.jpg


This is the original production FE30 (with a later cowl) - I didn't build this one - No noise/harmonics with an initial sharper curve (then going straight back)

shaft good.jpg

[Norwest]

Many years ago I posted on here about sanding the liner liner and the original poster asked and said it worked to a T and said thank you , so it should work here too!

[Norwest]

sport hydro 20

Check here on OSE, Steve has a chart regarding stuffing tube with liner and a chart without liner.

[rol243]

with some luck to might have to raise the strut closer to hull bottom after testing / trimming, if so you could add a slight bend in this log so help this issue and save re fitting another size.

[Norwest]

Check flex to see if the smallest portion has a tiny kink under the scope which maybe unseen by the naked eye. Remember the flex will vibrate in the middle of flex if the whole flex lay near flat. Coupler jaws spacing maybe and will show up right away just off the coupler tip and you'll see it right away if looked real close . Now if set screws in coupler have 3 screws , they can be used to compensate.

[Norwest]

rol- you could remove s/tube and add by soldering brass tube and use a next size bigger for a sleeve which will make a better curve. Do your bending before soldering which will make a bigger angle down.

[Old School]

Do not know if this helps but click on the FE30 image and a Word document opens giving info on setting up the hull and tuning.

http://www.insaneboats.com/setups/

[rol243]

I would firstly email Mike from ML Boatworks and ask him what is the good strut height for the 338 sport hydro and with abit of luck you might have your strut alot deeper than is required so this means you should be able to add a slight bend near where the brass log exits the hull to bring the stut to the desired height. if this works it will save you alot of extra stuffing around in regards to changing to another log etc. fingers crossed.

[IRON-PAWW]

Ok Thanks guys.

Thanks for the pics Tony. I do still have that FE 30 here you built me so I might refer to that as well regarding getting a better bend.

I spent a few hours at the lake today setting different strut heights and trying different props & flexes. I even tried bending the stuffing tube a little more. I was able to get the boat running better - but still sometimes I'd get the awful vibrations set in though. Just couldn't get it running smoothly every time. So I came home and ripped the stuffing tube out :-). Time to admit it just wasn't going to work the way it was. From what I found during testing - It does seem that just slightly more of a bend would probably help things. I'll go the 9/32 tube with liner and get a more pronounced bend and see where I end up. Live and learn. Watch this space :-) Damn nice boat the GSX380 when it gets up and goes... I'll say that.

[Norwest]

When flex came out, they found a small S in stuffing tube bend close to hull and thru the hull near coupler. This took the whip our of flex especially in the .130 flex. Make sure the s/tube is straight from motor to prop. Now if s/tube has a slight bend to either side of hull flex will whip, I found this out! Let the group know how things turn out .