Tuning help

[Rcizlife]

Hi everyone, I have an aeromarine sprint cat 42, set up with a tp power 4070 and a castle hydra xlx2. Running on 6s. I can’t stop the boat from hopping. I’ve added a ridiculous amount of weight to the nose forcing it to stay down, it does help but I loose so much speed, I’ve transferred weight to the rear and it still hops, fastest I’ve gotten it to is 60, strut is 3/16” from bottom of sponsons. Anyone have a cg point they recommend starting with? Tips

[T.S.Davis]

I've not run one of these but a reasonable starting point should be around 38% of the length from the transom. It can also require some messing with both elevation and angle of the strut.

[Peter A]

I had one with a castle 2028 in it. on 10s it did the same, it took half of the front or back straight before it settled. I made some trimm tabs 100mm long and bolted them on the transoms and it helped as did keeping the battery weight forward. However you need to find the balance between cg forward and turning. I have a 36"hull that I have started cleaning up to build and will set up on 6s.

[fweasel]

If I remember correctly, the Sprintcat has stepped, flat ride pads. Make sure those flat surfaces are true, with no concave pockets, and sharp trailing edges. If moving your Cg around hasn't gotten anywhere, I would start with a neutral Cg somewhere in the 33% ish range and and try tuning your strut trim angle.

[TRUCKPULL]

Justin - as Ryan stated - the sposon bottoms should be Blue Printed - Flat
Larry

[Rcizlife]

Appreciate the tips, Going to balance it at a starting point of 35% which is 14.5 inches. Start from there, and angle the strut downward a significant amount. Would the picture attached be a good starting point with an angle down? End of prop nut being level with sponsons , where brass enters strut that being 3/16 above sponson ..

[TRUCKPULL]

How long is your strut?

[Rcizlife]

Start here ?

[koen]

i run a AM sprint cat 36 i have cg on 30% from the transom this was also first with a nitro CMB 90 and now electric ,i have the strut 6/7mm above the sponson and flat ,i have tested a lot of props ABC ,Octura,TFL and Prather and the best handling and speed is with Prather props (i tested a couple motors TP 4070 1400kv,SSS4092 1400 and a Lehner 2260/8 ) Prather 240 and 245 are the best performers