Delta Force 35" trim tabs

[DISAR]

I have trim tabs in my DF35" but I think they are a bit small. Upto 75klm/hr (46 m/hr) it runs stable but over that speed I have movement pt-stbd like rolling and wondering if bigger trim tabs will be better.
DF35" owners, what trim tabs you have? Thanks

[Make-a-Wake]

They look to be placed way to far inboard.................

[DISAR]

oh yes, this is another issue, inboard or outboard?

[nova68]

Disar I run them inboard and outboard on my DF 33 and I have two of them and it works for me.

[siberianhusky]

inboard tabs will control the straight line ride, outboard the ride in the turns, big boat you could use both, I'd try shifting the CG, stinger angle, different lift prop.
I use trim tabs as a last resort, always try to set up a boat without them first.
As the speed goes up you may find shifting the cg will smooth it out. Even the rudder causes lift at speed. Try changing the rudder castor.
The faster the boat goes the harder it is to get it trimmed out at speed. The last few mph is the hardest. Some guys spend serious time and $s trying to get the last mile or two out of a SAW setup.
AT high speeds aerodynamics and hydrodynamics are working on the boat.

[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?

[Doug Smock]

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

[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!!!

[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??

[Alfa Spirit]

Did you run your DF without trimtabs?

[DISAR]

yes no good....

[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.


.

[Alfa Spirit]

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

[DISAR]

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

[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.


.

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%.