My first year with my 2006 Challenger 31 IDDc. Boats got a 550 HP Ilmor V10 and Bravo Teague XR Drive. Runs fairly well with a top- end of 70. Boat has no tabs or planes. No issues getting up on plane and it rides fairly flat. Past 60 mph porposing is an issue . Oh yeah the hull has a single 3" step. Seems like no matter how I trim it she like to porpoise. Would tabs cure this, or K Planes be better??. Would having K=planes add any speed at all??

Tabs or planes will slow you down if you ha e to drag them to keep the nose down. However, a good set of tabs will help with planing and effectively make the boat "longer" in rougher water.


I would repost this in the prop section noting what you currently have for props. Seems to me you ha e too much now lift and may have to look to a 5 blade prop or rev 4 to get the stern up.

Yeah, Try different Props. It seems you have too much Bow Lift, Your prop is picking up the bow to the point it cant pick it up or hold it up anymore so the bow drops and the whole event happens again. You would rather get your bow lift from trimming the outdrive, then you can add the exact amount of lift you need/want.

I used to think the same thing, until I purchased the boat I currently own. Couldn't figure out why I wasn't seeing the speeds previous owners were. One of the previous owners told me to add tab and I would find my missing speed. He spoke the truth. Gave me the 5 mph I was missing.

I told another buddy the same thing. He replied saying it was hogwash. A week later he called back saying he got the same results I did. Increase in top end speed.

Not saying this works on all boats, just saying that it's not necessarily fact that speed will decrease due to adding tab.

Buck

Could your hull have some rocker? Use a long straight edge on the aft section of the hull to get a good idea.

You are going 70 without tabs? Ummmmm......

W h y ?

True. Worked on a Checkmate I had.

The Challenger OS DDC was design by Harry Schull, Used to be a bigger single step, SPECIFICALLY for the Blackhawks, With HUGE stern lift. Trims would help, but I would experiment with props. The hull is almost identical to the AT hulls, (while Pat will debate this lol) .... But try to talk to some single powered AT boys and they might also help you. Both the Challengers and AT's single steps were reduced in the later years. The Blackhwaks vibrated to the history books. WE tested the Challenger hull. No.1... 32 DDc with (if I remember right a 7 1/4" step) twin 502 blackhawks in 95 and we hit 90. With John Simpson the original owner of the line. Good luck. Call Bret at BBlades for propping.

That hull is a complete one off; only a couple were built. Comparing that Challenger bottom to the DDC under the AT is like saying Fountain and Cigarette twin steps are "almost identical". The 32' (33' overall) hull Challenger DDC with twin 525s ran 10mph slower (as magazine tested) than the 33AT; which was bigger, longer, and heavier.

I would work with a seasoned prop tuner like Brett at BBlades before you invest in tabs, but I agree that you probably need them. I can't remember, but does the 31 Challenger have a notched transom as well? If so, that really confuses the water dynamics at speed.

U have the first 31 made by Challenger from MO. There was 3 of the 31 models built. I can not remember if your 31 had the bottom blueprinted but I know the other two 2006 models did after they were built. It made a world of difference in the ride of the 31. Also I can only speak for the other two 31's as they had Mercruiser 575's with Bravo 1 XR drives. The 5 blade Maximus worked the best for those apps.