Miss Geico dialed in- strut modification

[Speedracer128]

Ok thanks. Ill check when I get home. I'm on my phone now so I can't see the difference but I think I get what you are saying

[hydro_pyro]

I did this modification to my Blackjack 29 today. Night-and-day difference! I've got a little bit of mid-range porpoise, but then it flattens out and hauls ass with no bounce.

I usually run 6s by means of three 2s packs in series, with the third pack up front.

[Speedracer128]

Good mod. thanks for sharing the info. seems like it gives much more room to adjust the strut

[jeffrey1]

looks good.

[AlanD]

https://www.youtube.com/watch?v=_Uln02dfrSs

This is my run from Sunday. Still a little bounce at high speed. OSE has a new upgrade strut which should be released this week. I'll be ordering that soon with the M440.

[hydro_pyro]

That sounds like a solid 35000+ RPM. On the stock prop, you should be running in the lower 60's there. Very nice.

Try raising the strut a bit more vertically, while keeping the same down angle. You might need to bend the stuffing tube a bit to keep the strut aligned. This should give you even more stern lift to keep the back end high and loose to reduce porpoise.

[AlanD]

Thanks hydro. I did use some of your pointers on other threads to get it where it is now.

The prop is about 4mm from the bracket with about 2 degrees downward pitch and I did drill out the strut as shown above so I could get the negative angle and still align the ferrel on the end of the shaft. Make note that strut steel is bitchin' hard!! I used a stone grinding bit on my Dremel to do it.

I have some pics of my current setup in this thread if you want to critique my setup.
http://forums.offshoreelectrics.com/...r-mount-photos

[hydro_pyro]

I'm pretty sure that's all high-quality aluminum, but I could be wrong. Aluminum tends to wrap itself around the Dremel bit, clog up the abrasive surface, and sort of "burn" away while you're grinding... This can make it more difficult than some other materials.

I used a spiral-fluted metal cutter bit, and finished with a small stone bit.

[ozzie-crawl]

I know there different hulls but the last cat i ran a couple of years ago was a Mean Machine. They do seem similar in being not much depth in the tunnel but fairly wide.
The strut on that was around 1/4 of a inch up of the rear sponsons from memory.
Wondering if a strut with a short extension on the rear would allow prop clearance for moving it up more.
I think in theory it would stlightly lenghten the boat makeing it a little more stable.
Just a thought as mine has not seen water yet. You can also see in some videos were the prop wash is hitting the strut bracket this from memory would also cause some lift,if the prop was back a little it should stop this as well.

[hydro_pyro]

Simply moving the batteries far forward as others have suggested does not correct the problem. It just makes the front of the boat "plow" while the back end "digs in." Raising and angling the strut downward gives the boat the stern lift it needs, and the packs don't need to be moved as far forward, because the hull doesn't tend to trap air when it runs high and dry.

I ran mine again today on 4s and again on 6s. No bouncing. This simple modification is the ticket for this hull.

[tlandauer]

Simply moving the batteries far forward as others have suggested does not correct the problem. It just makes the front of the boat "plow" while the back end "digs in." Raising and angling the strut downward gives the boat the stern lift it needs, and the packs don't need to be moved as far forward, because the hull doesn't tend to trap air when it runs high and dry.
I ran mine again today on 4s and again on 6s. No bouncing. This simple modification is the ticket for this hull.

Well said! This should be a mandatory "Read before moving COG forward" notice!!!
BTW, the Proboat manual doesn't tell anything, on mine ( MG V1) they even got the prop thrust angle backwards, there is absolutely no excuse for that kind of misinformation.

[ozzie-crawl]

Had my first run today. Really happy for its first time out.
Will post a video up shortly and hopefully you guys can give me a bit of advice on setup.
Strut is up about 2mm from bottom of sponsons when hull is flat on the bench. Prop angled down a little. Its the most i could get with out mods the the bracket/strut. COG at 30%

[hydro_pyro]

Get out your Dremel and do the mod. You won't be sorry.

[hydro_pyro]

Here's mine... strut hole egged out, raised, angled, and aligned. No bouncing.

[ozzie-crawl]

Thanks for the pic. Mines not that high, will break out the dremel tomorrow and give it another try.