Dialing in a mono...

[Chilli]

I have a Titan 33 with Fine Design hardware that I just dropped a 1515 1Y in. With the new or shall I say Neu motor she ran strong but was chine walking pretty bad. The strut was set neutral and level with the keell. I got 47 mph out of her with a X640. I was hoping for a little more. Anyhow the B-mono guru in my club told me to drop the starboard tab a bit. I did and the chine walking was reduced significantly. When I got home, I did a little search on OSE and RRR and found numerous remedies for chine walking. Change strut height, change strut angle, change prop, drop port tab, drop both tabs, change CG.

Just for giggles, a few days later I ran out to the pond and set the tabs back to neutral and raised the strut up 1/16", keeping it neutral. This seemed to eliminate the chine walk but I was wondering if there is a preferred sequence in dialing in a new hull to correct porpoising or chine walking. Does using tabs increase drag more than making a strut adjustment. Does it not matter what you do as long as you get the proper running attitude? Or is it just a matter of trying them all and seeing which adjustment gives me the best GPS numbers?

[crrcboatz]

I have a Titan 33 with Fine Design hardware that I just dropped a 1515 1Y in. With the new or shall I say Neu motor she ran strong but was chine walking pretty bad. The strut was set neutral and level with the keell. I got 47 mph out of her with a X640. I was hoping for a little more. Anyhow the B-mono guru in my club told me to drop the starboard tab a bit. I did and the chine walking was reduced significantly. When I got home, I did a little search on OSE and RRR and found numerous remedies for chine walking. Change strut height, change strut angle, change prop, drop port tab, drop both tabs, change CG.

Just for giggles, a few days later I ran out to the pond and set the tabs back to neutral and raised the strut up 1/16", keeping it neutral. This seemed to eliminate the chine walk but I was wondering if there is a preferred sequence in dialing in a new hull to correct porpoising or chine walking. Does using tabs increase drag more than making a strut adjustment. Does it not matter what you do as long as you get the proper running attitude? Or is it just a matter of trying them all and seeing which adjustment gives me the best GPS numbers?

For me when a boat is acting up I want to start with the strut, then either rudder or tabs. Last is the turn fin.
Props is a quick way but the water conditions effects the prop more than most anything. So, with that in mind, it is changed after most of the other or above methods.

Curt

[Simon.O.]

As a slightly unusual idea, have you tried running the boat with no turn fin and no trim tabs.
Take all the gear off the back and see what happens, give it an honest run and write down on a note pad what you see.
Then feed in components one at a time. Trim tabs, and turn fin(s).

From there you will be able to see what each component does and how it affects the hull.

Strut changes alone can take battery packs of runs to evaluate let alone all the other components and thier effect on the hull.

I was told a long time ago by a wise man (JT) to take a pad to the pond and write down what you see as you see it. Read it all later and work from there.

I like to run a hull "naked" first and then work on tabs and fins later. Weight shifting can make a lot of difference too, left to right and fore-aft for balance.

If this is not news to you then that is great, I hope that it may help.

[DISAR]

I had similar problems with my mono 36". I first run the boat without trim tabs and turn fins, a lot of pulling and rolling to the right at full throttle. Then I installed trim tabs. These effects were reduced and after tests I also concluded the stbd tab a little lower than the port one. Slightly upwards from level. Trim tabs should be very little adjusted at a time, and as far as I noticed they do not inrease drag noticeably.
Then I also tested the boat with a bigger rudder, no effects at all but I could feel that speed and performance were decreased, so back to old rudder.
My strut is fixed. I also added a stbd turn fin but it only helps in turning which was not an issue for me. So it's pretty useless for me.
Another important thing to check is the weight distribution port & stbd. When you are at home, place the batteries inside as it is ready to run, and put the boat on a table and balance it with your hands upright. It should nearly stabilize with no big tendency to lean to port or stbd. If there is big tendency adjust the batteries position.

[tharmer]

Wouldn't you adjust the batteries so to partially counteract torque? It doesn't cause drag to do this whereas copensating with tabs does.
-t

[Chilli]

Well I did a few runs today taking all input into consideration. Tried a few things and I'm confident I'll get this boat running to my satisfaction. The most important thing I learned was that dispite all the good advice, you just have to get that boat on the water and try everything. I didnt do any scientific experiments. Just tried playing with the strut, CG and Tabs and observing how the boat reacted to the adjustments. I'll spare you all the details but the biggest improvement came from bringing up the tabs a few degrees positive. I even moved the strut back down even with the keel and still no chine walking. I also moved the CG back a little. Still have to play with her a bit more and maybe add a little weight. She definately wants to get airborn in the chop at full throttle. Thanks to all for your input.

[DISAR]

That's great you did it so fast. It took me months...

[andym]

The best advice I have seen on this thread so far is ONE THING AT A TIME, I start with a basic setting as follows, CoG 33%, tabs up 2mm, No turn fin, strut level and up 3mm. This is my starting point for all my mono's. I then see what each particular hull is doing and go from there one thing at atime and yes I do write it down. I have helped some mates with very bad handling boats both FE and Nitro setting up this way with good success

[Chilli]

I'm bringing this old thread back to life. I do have my Titan dialed in to my satisfaction, but had a question about strut height. When I was having problems with initial hardware adjustments, a very sucessful B-mono driver in my club suggested I set the strut level and even with the keel. And thats the way I have been running. It seems like I rarely see anyone set up their strut height level with the keel. I was wondering if this is causing unnecessary drag on the strut and increasing load on the prop causing more amp draw and slowing me down? She runs strong and cool. Just wondering if I can squeeze a little more out of her. Do any of you mono's guys have the strut set this low?

[Chilli]

Come on all you mono guru's. No theories on the subject?

[egneg]

I wish I could help Mike but I am going to be watching this thread to learn about mono's as well.

[Rumdog]

I've never had a problem with drag running the strut as deep as the keel. Normally I do run it a bit higher though. It keeps the keel a little deeper in the water and will help to eliminate chine walk.

[Flying Scotsman]

All, I can state is move the strut by about a 1 mm either up or down or angle on calm water and CG set properly, watch the performance and then move the CG for different water conditions and again compare

Douggie

[Jimmy Sterling]

I have been through the same situation with a H & M NS3, one of the hardest boats to set up I have ever owned I dont know if you have ever seen a NS up close but the keel runs very deep all the way to the front of the bouy and runs up to a very 'snubbish' nose.

I tried everything to get it to run right but to no prevail, the boat would always chinewalk and begin to porpoise towards the end of the straight aways. Anyway, long story short After many months of jiggling around with the setup I ended up with my strut about 1 - 1.5mm below the keel set at a neutral angle and my COG at around 38 %, yes 38 %.

Fixed all my problems and the boat went on the win the Thunder Down Under 2009.

I am aware that the Titan is a completely different boat but it might be worth moving your COG forward to where you would not normally run it and get the boat riding on the keel more, may settle it down ?

Worth a try ?

Jimmy

[Chilli]

Thanks for your input guys. I do want to reiterate that this thread was started a few months ago and I do have the boat running fine now. I just wanted to know if my strut height set up was highly unusual and/or detrimental to it's performance. I guess if it's running strong and cool, don't mess with it.

I've posted this pic before, but just wanted to update this thread since I brought it back from the dead. There have been a few modifications since I switched to the Neu. I added some rails to her to stiffen up the hull a bit more. I added 15 ounces of lead in her to keep her stable at higher speeds (Thanks Fluid!!!!). The added weight did not slow her down one bit. And I added a wire drive. My flex cable snapped and decided to try out the wire. I do like it!

A little hindsight on this thread for others. Especially newbies. There were two causes initially for my chine walk problem. First, I added a thru hull water pickup for additional cooling. And even though it was "low profile", it still caused excessive drag on one side of the hull. This caused most of the chine walking. Secondly, I have the trim tabs installed about 1/32" from the bottom. I started with the tabs at neutral and used this as a start point for adding negative (down) trim. But this initial setting was too low. One day, I decided to start from scratch and this time my starting point was two full turns of positive (up) from neutral. End of chine walk, but a bit of porpoising. I then added negative trim 1/4 turn at a time untill I got her running right. End of problem. Lesson learned: You just got to do your time on the water!!!