Delta Force 35" trim tabs

[DISAR]

Thank you for all this excellent information. It is actually true about the rudder, when I first tested the boat with a cut rudder it was forced to its port side and was wondering why?????? all my weights were equal pt to stbd, now I understand why, because of the flat sharp rudder bottom, I adjusted this by the trim tabs but then had a bit of chine walk. then changed setup and at higher speeds the chine walk was more noticeable.
Thank you for your information. I will round off the rudder bottom first and if no 100% cure then cut little by little

What do you think about the ride pad? sharp edges or rounded? or no ride pad?

[Rumdog]

Fluid is spot on with the long rudder statement. IME with monos, too long of a rudder will actually forct the boat to bank onto its port side and stay there. Even at wide open throttle.
I sport run, so I usually trim the rudder down enough to get rid of that behavior, but also like it long enough to turn left fairly well. It can be a very fine line.
I read a comment by Fluid a while back that said to start with a fresh rudder. (Buy 2 rudders) Trim it down just a small amount at a time, noting the length. Record how it handles at the various lengths. Trim it until the boat begins to handle poorly, then swap to the new rudder and trim it to the shortest length that worked well.
I've been doing this with nearly all my builds since. It only costs you the price of a spare rudder blade, and works excellent.

[Fluid]

No to a longer rudder. John Finch - who knows a thing or two about monos - states that a rudder can cause lifting of the right side and make the chine walk worse. Deeper rudders cause more lift. Round off the rudder bottom to reduce lift.


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[Alfa Spirit]

i have read where a longer rudder reduces chine walk

Yes, longer rudder or twin rudders

[steveo]

i have read where a longer rudder reduces chine walk

[DISAR]

A lot of boats with chine walk problems have a strut that is mounted too low. This lifts the boat too high and it rocks on the hull's vee, causing the chine walk. Offset mounting the strut makes the chine walk worse, especially by the end of the straight when the model is most effected by the prop lift. Shortening the strut by 12-15mm can also help this by letting the hull settle deeper into the water. Round off the bottom of the rudder, it can cause lift that induces chine walk.

The trim tabs should be mounted further out on the transom. In their current position they could be causing lift that upsets the boat's balance.


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excellent information, many thanks Mr.Jay. Maybe making the ride pad smaller can reduce lift as well. It is totally flat with sharp edges and has a width of about 0.78" (2cm). My rudder bottom is flat with sharp edges
I have moved the tabs outwards and slightly made things better but not 100%.

[DISAR]

I have not tested the racemaster that far yet, I want to finish the df first.........

[Alfa Spirit]

Do you have that problem with the MHZ Racemaster? DF hull is flat, the V on the MHZ is more pronounced

[Fluid]

A lot of boats with chine walk problems have a strut that is mounted too low. This lifts the boat too high and it rocks on the hull's vee, causing the chine walk. Offset mounting the strut makes the chine walk worse, especially by the end of the straight when the model is most effected by the prop lift. Shortening the strut by 12-15mm can also help this by letting the hull settle deeper into the water. Round off the bottom of the rudder, it can cause lift that induces chine walk.

The trim tabs should be mounted further out on the transom. In their current position they could be causing lift that upsets the boat's balance.


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[DISAR]

yes no good....

[Alfa Spirit]

Did you run your DF without trimtabs?

[DISAR]

Ok after reading some threads and saw some vids related to chine walk my boat is doing the same thing. at WOT the boat chine walks, not heavily but I can loose conrtol easily, so far I did 55 mph with a 447/3 cut (1521 1Y, 6s2p).
How can I eliminate this chine walk????

tabs are neutral, batteries are on the sides (pt & stbd)
now I am blueprinting the hull, which one is better ride pad or V??

[DISAR]

Hi

Yes, this is my current setup. The trim tabs are placed a bit inwards and there is a distance of 44 mm between them (edge to edge). I do not have any chinewalk, I eliminated this by offseting the shaft 2mm to the right. The boat runs straight at full throttle and then starts moving from left to right and vice versa repeatedly, slowly in the beggining but gets worse if I keep the throttle full. I tried with various props (225,445,447/3) with NEU 1521/1y 6s2p, I have reached 53 mph top speed but can't keep it for long because of this rolling. as the speed goes up it starts rolling......
because I have this offset of the shaft, the trim tabs should be placed at equal distance from the shaft centre line or from the boat centre line?.....
Many thanks!!!

[Doug Smock]

Is that a pic of your current set up? If not do you have one?
Rolling, do you mean chine walk?

[DISAR]

good information. so shall I keep these ones and add two more, or shall I remove them and add bigger ones? to eliminate the rolling?