Need for speed

[Jesse J]

I don't know what you are imagining when I say bench test. I simply hooked it up and tested the throttle to see that it was going the right way. switched two wires and tried it again, just a flick of the throttle... I wasn't saying I opened her wide open on the bench... I don't see how you get it straight before you hit the pond if you don't make sure your radio works?

[Jeff Wohlt]

Jesse, what you are doing is common and fine. Reving it way up or holding rpm as Jay suggest is what does damage. Motors do get very hot fast this way.

You have not been in this long but seeing how far you have gotten is awesome. Exciting to see people really getting hooked on FE boats. Keep it up. That is the fun about this.

Talking about frustrating...you should have been around when we were using low powered 1700 cells and 05 motors. It really was about the set up so much more because of the low power and cells we had. Prop it wrong and you could not even finish a race...that is unheard of today.

Can't remember how many times I melted heat shrink off my 207D ESC and damaged cells. Asking for 50 amps when the cells were only good for about 20.

I could not even really turn the pletts on until the 2400 cells came out. Most of us had PVC cooling tubes with fans on the end to cool the packs off qucikly.

[ozzie-crawl]

remember when nicads went from 1200 to 1400mah wow power to burn lol
jesse do you run trim tabs? these hulls have a small ride pad near the transom thats were they like to run but can be hard to run them on it with out trim tabs.
weight shouldnt be a real issue as i have ran mine 4s2p ,batteries weighed 820grams water was up to the top of the transom at rest

[Jesse J]

trim tabs yes, water at/over transom, me too. I noticed HUGE improvements when I raised the angle of them just a bit. Also, I think I need to move them down - they were installed sloppily and one is about 1/8" up from the bottom of the hull - not flush.

Jeff, I hear ya. My first "FE" boat (early 1990's) was an electrovee with an astroflight controller and an 05 motor with that cheezy brass water cooling, and funny, I was running 1700s as well (Dad called them my "hot" batteries! You are right, I have not been in this high tech truly FE world long (got hooked back in when I found the set of Garry Finlay plans for my first FE build since - in fall 2007; incidentally my avatar).

My main purpose for this thread was to see what set up would be best for this boat, and now I would like to keep it at 4S. So I will tweak my BJ motor/esc combo some more with my freshly b/s X445 and see what kind of terror I can produce at our community pond.

[D. Newland]

Can you post a few pictures of your transom, both from the side and rear?

[Jesse J]

This is all I have already taken, will take more with this problem in mind later tonight/tomorrow. The one seen in the oblique shot is the culprit, the other I can drop flush. I need to redrill either transom or tab. Are they backward? I see the angle on the outside not the inside???

[Flying Scotsman]

Your trim tabs are not flush with the hull surface, also they look not equally spaced, and your turn fin is too far to the right.

Douggie

[Jesse J]

Good observation, factory job, my discount tradeoff I guess. It sounds like I might need to take everything off and start over? How do I position the turn fin better? is there a formula for this? or just as close to the keel as hardware allows. What do you suggest Douggie? Thanks for the help, I need lots. Oh, by the way, this strut is pre haircut, I trimmed off one inch, it is now 2" long. and I added another turn fin on the left. I will update current config soon, but other than these slight diffs, it is the same.

[Flying Scotsman]

A very hard question to answer. The turn fin is always a point of discussion some like it parralel to the hull angle, some like it at 90 degrees. Yours is neither as it is offset. Send us a pic of the new configuration.

Douggie

[Jesse J]

I am after 90degrees to hull. How can it be parallel to hull angle- do you mean vertical parallel to rudder, or parallel to opposing plane of the hull-in this case more towards horizontal? New config will only show second turn fin as diff.

Would it be a good idea to move the tabs toward the keel (say leaving 50mm gap for 45mm prop) and shift the turn fins down as well?

I kinda liked the design that if they are up high-near the chine, then they are more out of the way when full speed on the straight. That said, I have noticed that full speed on the straight there is a tendency to set up some wobble that could be due to this...

[Flying Scotsman]

I am after 90degrees, how can it be parallel to hull angle- do you mean vertical parallel to rudder? New config will only show second turn fin as diff.

Would it be a good idea to move the tabs toward the keel (say leaving 50mm gap for 45mm prop) and shift the turn fins down as well?

I kinda liked the design that if they are up high-near the chine, then they are more out of the way when full speed on the straight. That said, I have noticed that full speed on the straight there is a tendency to set up some wobble that could be due to this...

Nope. The hull angle on all boats are different. If the turn fin is at the same angle or like the trim tabs to the surface of the hull. 90 degrees is the same as the rudder.

Douggie

[D. Newland]

Trim tabs: I like the placement of the left trim tab, so I would mirror that measurement and install of the right tab. Also, both tabs should not be level with the hull bottom. Mount them 1/16" to 1/8th" above the hull bottom.

I like left turn fins, even on my oval boats.

Rudder: Leading edge of the rudder should be even with the drive dog. If you shortened the strut, you'll need to then look at shortening rudder bracket.

Rudder length. You may be OK here, but lay a straight edge flat on the hull bottom and have it touch the rudder, then measure the rudder length from this point. I'm curious to know how much rudder is actually in the water.

While you're at it, take an interior shot with batteries in place, too.

[Flying Scotsman]

David, the trim tab position you propose I find very interesting. As, I am also learning. What is the benefit and please note David is a very experienced racer.

Douggie

[Chuck E Cheese]

check out this thread... ammo 2300 with stock BJ esc is no prob on 4s. the 3 cell set-up i am running is killer, 8L/hydra 120/ 3s-4900/4 or 638. watch out using those big props with little torque. i actually go faster with a 38mm than a 42mm. the R's come way up and it screams.
http://forums.offshoreelectrics.com/...ight=1st+build
this forum has all kinds of info on this boat.

[Jesse J]

Ok, I got some useful shots of the rearend of the Red Devil. Hope this elucidates my setup. Thanks for your input!