Trim guide and hull tuning questions

[jester_s1]

I've done some searching for a definitive trim guide for Deep V boats. I just got a DF 33 which runs stable but I think it's too wet. I've been flying model planes for about 11 years now, and we use these detailed trim guides that give a nice sequence to go through to trim out unwanted characteristics and get a model performing to its best potential. I've found some guides explaining raising the nose and lowering it, which was easy enough to figure out with basic physics. Are there any guides that go deeper than that?


My other question is do many monohull builders take the time to flatten the bottom of the hull and sharpen the trailing edge at the transom? When I had a catamaran, blueprinting the sponsons was a necessity. Obviously, the trim tabs are set right at that rounded edge at the back, but I can't help but think a smooth transition would be better. Is this a significant factor, or am I overthinking it?

[martin]

A good starting point for cg on a mono is 30% forward from the transom, Also check the last 25% of the bottom with a straight edge to see if theirs any hook ( hollow ) as this will suck the boat down onto the water causing it to run wetter with the bow down slowing the boat. If the bow is down a bit you can also raise the bow & get it to run looser by angling the strut up prop end ( positive angle ).

[Fluid]

There are many tuning guides out there, some better than others. These are two of my favorites.

http://rcboats.kiwi/index.php/ct-menu-item-15/ct-menu-item-31/ct-menu-item-33

https://rcraceboats.webnode.gr/news/monohull-speed-secrets/

.

[M3Bluegsr]

I have one of these, easiest thing to make it ride less wet is to adjust strut or move CG back, CG is usually first adjusted by moving batteries. Post your setup or pictures of the setup to evaluate. The DF 33 rides on the small flat ride pad at the rear of boat.

[Scottyk]

I noticed on my Rio51z gas boat that the prop choice can make a huge difference on the attitude of the boat. I purchased one that was recommended to me and was apparently a high lift prop, this made a huge difference and slowed the boat waaay down by noticeably pushing the nose down and making a huge rooster tail behind it. The correct prop and trim tab tweaked up can now almost blow the boat over.

[jester_s1]

This is looking as straight as possible down the keel. The drive definitely has some angle pushing the stern down, which I think I'll reset to neutral. I also think I want to go ahead and get a better prop. The boat has a slow motor, a Feigo 580 8L. According to what I read, that's a 1649kv motor. I'd rather stick to 4s power because I used those in my trucks. So would I be on the right track to look in the 45-46mm range, detongued and cupped?

Sent from my SM-G900P using Tapatalk

[M3Bluegsr]

Hardware looks ok, can I see the inside of boat to see layout? Definitely make the strut a neutral angle, if you feel it is pushing the nose down while running.

This motor will run 24,420 rpm on 4S (3.7Vx4S = 14.8V, 14.8V x 1650kv = 24,420rpm), This is lower in the rpm range, so you can use a larger prop. You can move up props until you are happy with or balance the boat's amp draw, performance, run time, and electronic heat. So to suggest a prop, what is the esc's amp rating, the battery capacity (mah), and how long would you like the boats runtime to be?

[jester_s1]

I'm using 5000 mah batteries, the esc is a Turnigy 180 amp, and I'd like to be able to run 6-8 minutes at WOT.

[jester_s1]

Another question- is it common practice to really sharpen the leading edges of rudders and turn fins? I'd think there must be some gains to be made there.

Also, the plumbing is set up with a single water pickup and cooling line. The motor has both a jacket and mount cooling. Is this adequate, or do these boats really need dual pickups and outlets?

[M3Bluegsr]

I'm using 5000 mah batteries, the esc is a Turnigy 180 amp, and I'd like to be able to run 6-8 minutes at WOT.

For 6 minute run time that would be about 50amps continuous. It's hard to know amp draw of your boat with a specific prop without testing. A general calculator I used, suggested something in 43MM range, like a X642. Maybe someone else will post with some other suggestions since we have a better idea of boat/goals.

[jester_s1]

What do you have on yours, M3Bluegsr?

[M3Bluegsr]

I run 180A esc, Leopard 4082 -1600kv, usually on 5S. It is not very pretty, got the hull used and was in bad shape, but cheap. Still have to paint it, at first did not think I would like this boat as much as I do. I will change the voltage and prop size depending on my mood. Some days I want to see how fast I can go, other days I do laps for more runtime. I believe, I have mainly ran a 42mm 1.4 pitch (X442) on 5s. Might not be the best prop for it, but one of the ones I have, and seems to perform fine.
IMG_0217.jpg