Sorry gang, trying to keep up, and not doing it very well lately.
Anyway, Call John Janaky
DAH Pro-pellers
34111 Washington Ave.
Burlington, WI. 53015

Measure the X by measuring from the pivot point on the transom assembly down to the lowest point of the keel in the center of the transom.
For approx. numbers, 14" to 15" is pretty standard for recreational boats, with most race boats and high end performance stuff up around 19 or so.
(APBA Factory 1 rules had a limit of 19" for step bottom boats and 19.5" for straight bottoms like the 25 Thunder).
I'll measure mine as soon as I get a chance.

Thanks Gordo for the info. I'll wait to hear from you.
Mike

Hey Gordo,
Was wondering if you had a chance to make it to your boat to get the X dimension measurement ?
Also wanted to clarify something with you. When measuring the X-dimension it is taking from the pivot point of the lower unit. which pivot point the up and down or the left to right?
I couldn't seem to get a number in the range that you gave me so I want to confirm.

Thanks,
Mike

Sorry for responding late Mike, been busy preparing for and recovering from Hurricane Wilma...Seems like Gordo has jumped in and answered many questions. A bone stock 25 with an Hp 500/bravo will run upper 70's all day long. Tweaked with the right X-dimension and prop you may get over 80 mph which is great for a 24 degree hull that measures 24'6" down the center line!! The greatest thing is the mid range accelleration in that boat when powered by the Hp 500 carb or efi. The boat is very throttle responsive and a joy to drive.

Jupiter Pulsare,
I wish you luck with your rebuilding from Hurricane Wilma.
What kind of props do you think worked best on the tantrum with the 500HP?
Thanks in advance,
Mike

HEY MIKE WHATS NEW, DONT FORGET THAT HERE IN PA WE ARE 3/4 MPH SLOWER THAN RUNNING AT SEA LEVEL IN THE SALT. I THINK AT 74 /75 YOUR ABOUT AT THE MAX W/ YOUR SET UP. WHEN I BOUGHT THAT BOAT FROM THUNDERDAN HE TOLD ME #S I NEVER SEEN UP HERE IN PA AND HE RAN IN THE SALT AT SEA LEVEL. ALSO MY 32 AUDACITY WENT 91 IN THE SALT AND BEST I EVER SEEN AROUND HERE IS 87.

32 THUNDER RICK

Hey Mike, if I remember correctly (??), we were swinging a Bravo one 26, Lab finishing will give you an extra 2 mph at wot. By the way, Thunder Rick is correct. The boat will run faster in the salt water (more bouyancy) and at sea level (more oxygen to feed those hungry cylinders). Pat could give you better feedback on prop choice....he's got more seat time in that boat than anyone. The reality of a 25' Tantrum is that when the water gets snotty, that boat will crush it's way through and leave other similar sized boats in it's wake!!

You are sooo right Steve!!! I've lost more pairs of sunglasses turning my head to see how far back everybody is!!!
How are ya by the way?

I'm great!! The boating in Jupiter, FL is so much better than Ft Lauderdale. No where's near as crowded and lots of places to hook up with other people. No seawalls!!, just nice sandy beaches along the intercoastal and some great sandbars to hang out at! The performance boaters in the area lean more towards smaller outboard powered boats than offshore I/O's and some of them take it to the extreme!! I've seen guys running 20' STV's and Allisons at over 100 mph GPS and they still want to go faster!!! It's one thing to run that fast in a boat over 35' but it's entirely another feeling when the boat is only 20' long!!! We do have a few Offshore boats running around. Seen a couple TS TopGuns, A ridiculous Outerlimits, a Skater with tripple 300x's, a Fountain now and then but no Active Thunders. Pat may have to "loan" me one some weekend so I can rattle some cages! LOL (Then again, He'll tell me to buy one!) LOL Steve

Rick,
All is good here. I'm just trying to dot my I's and cross my t's with the boat. I still want to try to dial the porpoising out if I can.
I'll have to keep digging on the prop issue.
Be good.