260 Baja stock
 

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..http://www.gamingkrib.com/tzhs1982/images/prop.jpg
http://www.gamingkrib.com/tzhs1982/images/91.jpg
Any help appreciated.

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

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

Try some other known stock propellers to collect more data.

Brett

data
 

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..

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

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

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.

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.

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!!:evilb: 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.

Ya, i will have to also look that way when I take it out this week to add the new sun pad. cockpit has no foam. The boat has a four holes in cockpit, two I looked at showed no foam...I could drill around the back sides and open them up -and drill inot the stringer and see/feel. The transom looked fine around inner gimbal ring but i heard/read they skimp on the sealing of screws around tabs so i can check that. As for ride, the bow rides nice and handles rough water very good compared to other boats i have had, and i have had junk hulls and my Fountain. I feel it riding the pad correctly. I'm hoping the four blade will not take the bow lift away as one of my mechanics claim. Brett also mentioned it might have bad hook or x dimension off. The previous owner claims it did 55. Yes, sat for 4 years covered with mooring cover...cleaned up nice though. Never owned a Baja, thought they were too "bubble" looking but this model year sparked my interest. Though I miss my Fountian very much.http://www.gamingkrib.com/Fountain.jpg

I have always had a lot of admiration for Reggie and his engineered approach to everything he does.

You know you can't compare the Baja to a Fountain...

dtile cant wait to hear how this prop works out for you. I sent you pm last week i am having a very similar issue with my 241 liberator in fact its sounds almost the same with ever manor of the issue. I am thinking tring the same prop i have tried a mirage plus 23 and regular mirage 21 both having about 25% slip. the 23 was faster at a lower rpm than the 21 but it should be... got 44 at 3900-4000 with the 23 42 at 4200-4300 with the 21

Thanks Brett for the info and help..found a Rev 4 unexpectatly and had it labbed locally by an old timer down the street...
fyi
Stock Michigan SS 19 39mph 5200rpm max (slips, needs planing help)
Stock 21 Mirage 43mph 4600rpm max (slips, needs little tabs)
More cupping added 21 Mirage 47mph 4500 rpm max (slips, needs little tab)
Rev 4 21 Stock 48mph 4600rpm max (no slip, nice accel, little bow lift, no tabs needed)
Rev 4 21 Labbed 53mph 4900rpm max (no slip, nice acceland and cruise, bow lift much better, no tabs needed for plane, rpm too high)

Glad it worked out well.
I'm glad you took my advice..........

Should I send a consulting bill?

Just kidding, LOL, we have people call for advice every day.

Brett

Options...not advice...they blame YOU on advice. ;)

In this case the 21 Rev 4 was my advice. What a difference in your numbers from the original!

Your right, if something dosen't work as planned, it's always the propellers fault.

Let us know if we can ever help in the future.
Hope your road to recovery continues.

Brett

Hmmm...Rev 4 @ 21 Labbed...kind of gets me thinking except maybe 23" for my rig. Getting close...we'll see.

Sorry to come along so late on this thread, but I just found it... The YouTube video link in an earlier post is of my boat... It has a completely stock 7.4 in it, and tops out at 57 MPH (GPS) in relatively flat water... One person in it or six, same top speed... It may take a little longer to get to top speed with more people, but we are talking a very insignificant difference in time.

The prop is an untouched Mirage 21, top speed comes in right around 4800-4850 rpm. The boat handles rougher water with relative ease. In the video, there was about 18"-24" chop... 55 mph in the short distance covered in the video, after a turn... Hope this info helps the OP, albeit a bit late...

Hello,

I calculated your potential speed with a 21" pitch prop at 4600 rpm. With the normal 10-12 % slip usually seen, I've come up with a speed of 52-55 mph. This is far higher than what you are getting currently. Calculating the speed potential based upon boat weight, slip associated with most 26 ft. boas weighing 4500-5000 lbs, and available horse power, I come up with 50-51 mph. Having said that, you are still getting too much slip. There are 3 distinct reasons for the high slip. please feel free to call 330.425-4266 and I will be happy to review these slip possibilities with you.

Most 26 ft. boats with twin 260's and Alpha drives run between 58-62 mph properly set up. 50 mph on GPS is a reasonable target speed for your application.

I look forward to your call.