Dtile

Hello all! Just bought and old Baja coming from a 35 Fountain. Yes, down sized for health reasons. Very frustrating, might add since my 35 had twin blowers w/ speedmasters/cleavers... Anyways, bought boat as little project (was a mess) with son and I and getting frustrated on some speed tests -among other small issues. Though I'm no mechanic, i always try to leave the "hard "stuff to my mechanic...i can turn a few wrenches and diagnose on occasion. I'm getting 43mph max on GPS out of this 260 with stock 1991 7.4 / Bravo 1 thru prop exhaust. I feel no real "bite" from 4k to 4600 rpms. at 4k it does around 40 mph. I have replaced coil (was arcing), wires, plugs, all fuel (run 93 octane and at 10 advanced timing), exhaust among other non related items. Had Carb rebuilt as well last week. Motor has 200 hours but wasn't used a few yrs. Runs nice actually. I did have a similar boat and size in the mid 90's that I know did in the low 60's with same set up. Most people with same setup and prop are running mid 50's. I'm trimming the boat fine and my tabs are in the right place. I get a max 4600 rpm and the prop is a Mirage 21 SS. What ya think this boat should get at WOT? I had 1/4 gas, and only one passenger when testing on GPS. River was calm, slack tide.
Enclosed pic of Bam's Prop Calculator. Slip seems horrible at 28 % -my prop guy looked at prop and stated all looked fine but could add a little cupping if wanted. Any ideas -go to 4 blade? Though only a Mirage, a Mirage Plus 23 a better fit?. What pitch 4 blade? I would like cruising speed better, i don't plan on running at WOT like the old days. Boat planes fine. Would like to pull skier/tuber..

Any help appreciated.

bbladesprops

Slip is too high.
A Labbed 21 Revolution 4 just might be the ticket.
Need to figure out why the slip is so high. I think your current prop has issues.

Brett

bens87241

Did you figure anything out. I have 241 liberator running the same motor drive prop combo getting almost the exact same number and same slip issue if you figured anything out let me know

bbladesprops

Try some other known stock propellers to collect more data.

Brett

Dtile

I had the prop cupped better buy a local guy to see if it would help, gained 2 mph but still unable to get above 45. HE claimed the pitch is stock. A little less cavitation now...I upped timing to 10 Degrees, boat runs great, all new gas 91 oct. I think the Mirage (non plus)isnt gonna do it and will try the 21' Rev 4 from Brett...left mg with him...today was dead calm and my WOT was at 42...boat likes chop..again, a new used boat for me. Just feel cruise speed is horrible and WOT is a mystery. Pulls a skiier/planse fine still..

Dtile

Tried a 19" today for shoots and giggles...ran 5200 rpm and WOT was 39 mph gps...

bbladesprops

Dtile,

I didn't see the message on the machine and Brad didn't get one either.
We can absolutely send you the 21 Rev 4 for testing. Please call again and we'll make the arrangements.

Brett

sprink58

The Baja 260 is a relatively light boat...less than 5000 lbs dry. From the text of your post it reads like the engine and drive are strong and that the WOT rpm is close to where it should be.

This is a long shot...but is there any chance that there is some water logged foam or any other way water could be captured in the boat? Also..did your local prop guy check the prop for hub slippage?

I think this a video of your boats twin running 55 MPH which sounds about right.

http://www.youtube.com/watch?v=kpFBtIDBnEw

Good luck with this...this is certainly an interesting question as to why your boat doesn't perform as well as the one in the video.

Dtile

HE claims the hubs don't slip, they just go when they go...although sometimes it feels like it is slipping, he thinks just blow out. Bought a 21 Rev 4 which is on its way...yes, thinking water too if this prop doesn't work...http://www.rotdoctor.com/index.html ..I have used before on some other old boats and turns the wood into Rock (CPES)...Thanks for asking though. I'm not sure this boat can do 55 on GPS still, Im shooting for 50mph with a nice cruise speed.

sprink58

Seriously..I would arrange to roll that boat across a set of certified scales at a salvage yard or something similar to get an accurate reading of what you are working with. If it nets out with less than 1/4 tank of fuel and no gear...significantly more than 5000#...I think you found your problem.

It sounds like you know your way around boats and have experience as to feel. Let me ask you...does it "feel" heavy...or does it have that "light" feel like Baja's and Fountains do as opposed to a Formula or a Cigarette? Has it been stored indoors or has it been exposed to weather? Does Baja foam the tank in and fill all the voids beneath the cockpit floor or is it clean.

I was afraid I had water in my Formula 255 Liberator because of the way it pulled on the steel "home made"trailer that I bought with it. When I bought a new aluminum trailer just for info I had the boat and trailer weighed at the trailer factory. The old steel trailer weighed 3200# vs the new one weighing 1100#!!! Don't think for a second that I didn't feel that difference as soon as I left the lot!! My boat and trailer together weighed 8800# when I drove in on the steel trailer and 6700# when I left!! I had about 700# of fuel and 200#~300# of anchor, water, lines, gear, etc. My boat's advertised "dry" weight is about 5650# with twin SBC's.

Consider having it weighed regardless...I think you should already be seeing 50 at this point with the props you have. If it weighs heavy I'm thinking you have wet foam that can be removed...it's a job but not the end of the world. I would guess that if it is foam that most of it is below the cockpit floor which is relatively easy to remove.

In any case...let's see what the Revolution 4 does for you. I'm probably going to use a pair of 21" or 23" on my 400 horse SBC/Bravo combo so I am interested in the result.

Again...good luck with this and post what you learn.