Coleman231

Alright, need some knowledge dropped on me.

Finally got my long project in the water to start getting the bugs worked out. I have tried just about everything to get on plane quicker! It takes FOREVER.

Boat is a 1996 wellcraft thunder 38. Full cuddy. Running SSM IV set 1.5 inches below hull, with 17.5 diameter 28 rake blades. Motors are 588 ci brodix headed with 1071 blowers currently set to be about 6 lbs of boost.

I have tried gradual increase, I have tried 1200 roll into 4000 rpm and hold, hold at 3500. Tabs in just about every conceivable position. All end up in a long long process before she starts to nose over. I have seen the aerarator tubs on a lot of big boats with SSM VI drives....so just looking for knowledge and experience as I keep refining this thing.

CDShack

Not the same, but here is my experience with surface drives on a Scarab. I bought the boat and tried everything, damn thing would NOT plane. Called the guy that sold it to me and told him the boat was having problems. He laughed.

He told me to trim down the drives and tabs and push the throttles to 4200 rpm (unanswered rpm-eek!) and hold it. When one drive catches, throttle into it, and the other will catch, then throttle them both up. Did it and it worked like a champ. In the many many years I've owned the boat since I now can feel the way to throttle out and can come close to a Bravo on speed coming out of the hole. It was unnerving learning, but after you get it.....piece of cake!

Coleman231

Thanks, in searching yesterday I read some said in a formula they hold about 4k until they feel a bite.
I tried rolling In slowly, holding at 3500 for a bit then coming up to 4k, tabs in all limds of placements, always with the drives all the way in or just out enough to be level. Ill try being more aggressive this next time out. Ill roll them into about 4200 amd see if i can get them to bite a little quicker.

I have got it on plane each time....but holt crap, it probably took a football field lol.

frickstyle

Coleman,

I have similar issues, with surface drives, in an old 38ft boat. What I've concluded is that you need to run big diameter, and also, yes pin the crap out of the throttles. I hate doing it because it's tough on the engines, but sometimes that's all that works.

Sometimes I will run the tabs up to gain speed then lower the tabs to help push the nose over onto plane. Other times I will do the opposite. Are those the same props the prior owner ran?

Coleman231

I bought tye boat as sn empty hull, previous owner had bravos on it.
went ahead and learned a million things in rigging a boat by making my first one a heavy big boat that we built big blower motors for, cut and hung surface drives, then moved and aligned motors lol. Long learning process. I have built and chopped up some pretty fast card, but this was a whole new animal!

Once on plane she was rolling pretty freaking healthy for such a big heavy boat. We were rolling 58 on gps at 3500 rpms. So I think when I lean into her, she is going to move out, just gotta get on plane with needing the length of a short runway lol.

ICDEDPPL

iTrader: (1)

YOU need props with more cup. There were props with low cup (below .050) i could not even get on plane with , just burning a hole in the water . Props with lots of cup ( .130) would roll over at 1800 rpm like a bass boat .
That being said f the cup is at least .075 I would have to hold it at 4400 for a while to get on plane sometimes 5000rpm
No load on the engines so not hard on them just gotta make sure oil temp is nice and warm .

Wally

iTrader: (1)

This is not an apples to apples comparison but the very first boat i bought (1987 Baja 320) came with a set of speed-master type cleavers the guy said he could never get to work....It was a TRS boat. I threw them into the garage and forgot about them. Few years later i had a 30' Scarab also with TRS and after rebuilding the engine i needed bigger props and remembered about the cleavers. Put them on and the boat would just stand the nose on end and boil the water behind it....it would eventually get up and over but i didnt like not being able to see whats going on in front of me. I did finally figure out a routine that did work though. I stabbed the throttles to about 3500 and the nose would come up and the wake off the back end would build.....i cut the throttle back..nose comes down and as the wake comes up and hit the transom it pushes the boat forward and that's when i jam the throttles back up and up she goes. The boat was faster with the cleavers i just never like the starting procedure to get her going.

CDShack

I forget to ask; how many blades? When I first bought my boat it had 3-blades, then I went to 4-blades and it came on plane better. I have just purchased some 6-blades, but have never run them, so we'll see what happens! LOL!