25% slip
 

27’ Fountain single step
18.5” X Dimension
Bravo upper standard height IMCO lower
1.50 ratio
280 K planes
28p B1 - new out of the box

540BB, Dart heads/intake, hyd roller w a 1050 ProSystems. Made 640/630tq with standard headers so not sure what it’s actually turning at the shaft.

Had a 26p B1 on it and the boat will run 72-73 @5800. Picked up a new 28p B1 and it runs 72-73 @5400. Same mph and roughly same slip %. I only got to run it a couple times with the new prop before the season ended.

Plan to really do some testing this spring to feel the boat with different trim / tab adjustments and capture slip numbers. I’d really like to test mid range cruise. I know it should be higher, but may help put together what the hull likes. Typically at WOT I’ve got the tabs all the way up and drive around 4-4.5. Maybe I’ll get it dialed in with seat time, but wanted to open up props for conversation.

I contacted Brett last fall and I couldn’t find the email
so maybe he called me back, either way he seemed to lean towards me needing to address the slip before fixing it with a prop. Maybe he’s on to something because the new B1 made no difference other than a drop in RPM - which was a positive.

I see a lot of Fountains running Hydromotive and one guy said a Maximus really helped, dropping slip by about 10%.

The boat runs fine, but I’d really like a little more top end out of it and feel it’s capable.

Thanks

Swap the imco lower for a std bravo or xr lower

Appreciate the suggestion. Can you elaborate? Thanks

Do you have any pictures of it running at speed? It seems it must have a lot of "wetted" surface, it's like it is glued to the water or something.

I wish I did. Don’t have any buddies with a boat. Short of dropping my family off on the bank and having them video me :D Thought about a GoPro in the side mount may help. I do know once I trim it up it starts to chine around 70, so I have a feeling it’s on the pad.

Not a Fountain owner but my Velocitys always ran faster with Hydromotive. Reggie used to ship his single engine boats with a Hydromotive prop until Mercruiser put the screws to him and made him use Bravos.

Padraig

below 80 the imco nose cone hurts more than it helps. I tried one on a 27 fountain years ago, went to a -2 and it was 1-2 mph slower than the stock lower.
Every other boat I’ve ran an imco on that was slower than 80 or didn’t need the shorter lower ran slower.

Thanks. I haven’t looked into it much but could I put on one of those aftermarket nose cones possibly?

Why do you want a nose cone? There no need for one under 80 mph. The standard lower lets plenty of water around it for the prop to grab.

Mainly from ignorance. Did some reading and see your point. I am curious though your thoughts on switching on the IMCO for a B1 or XR. Thank you

Do you have a standard length lower or -2? Either way you could run a spacer and drop your current lower down instead of replacing....might simply be too high of propshaft height making it slip. Just a thought.

Also to your logic earlier....chine walk does not mean it's on the pad....you will know when its on the pad..the whole boat will lift and feel much more free and yes it can chine walk however it can chine walk just as easy not on the pad.

A 5 blade...maximus, max 5, hydromotive whatever you choose could and would probably help.

FWIW I'm going through this on my 28 nordic but mine is becoming more of a having trouble carrying the bow and not so much a slip issue however they both are related....mine has a heavy big nose whereas yours doesn't so I suspect if you have a -2 on it that's your problem and a spacer will help...the guys with stepped nordic heats which is more similar to your boat found that they had super high x dimensions and -2 shorty lowers hurt performance drastically and even a spacer lower than stock helped those boats....just another thought

How deep is the prop shaft in relation to the bottom ? trimming 4 4.5 ? Id take a look at the drive in that position you may over trimming

If the X dim is 18.5, then the propshaft would be about 3.25" below the bottom with a standard length lower.
X Dim/crankshaft center to Prop shaft center is about 21.8 inches
I would install a 1" spacer.

Thanks Griff. I actually used your method from a 2008 post on measuring x dim. Measure from bottom of hull to transom assembly and added 9.25”.

Are you thinking to reduce slip by getting more water to the prop or stern lift etc.?

i,m pretty sure reggie used a left rotation prop to help with torque not sure if it helped or was a gimmick

I’ve got a LH on it now so must’ve been a gimmick lol

I tried a set of Hydromotive's on my twin 35 (non-step) a couple of years ago. I could not believe how good the boat tracked, turned and top speed was better than anything. Bad news was it would fall off plane at around 33MPH. Took them back to the shop to see if he could fix the low speed falling off plane. Nope, settled for Bravo 1's.

Couple of things. First, do you have a drive shower installed? I would remove it if so for any prop testing as some of them can cause cavitation
Secondly, I have been where you are at a couple of times with slip #s in the low 20's. These were on boats that ran around 75mph and I was trying to get to 80+. You probably have a faster hull than mine were, think West Coast stuff. A 5 blade or a drive spacer will most likely lower your slip and possibly pick up some mph. But not all slip is bad slip. Think of the Bravo drive as the 10 bolt chevy of drives. At some point you will get the drive hooked up too hard and it will self destruct. Once when I added a spacer I lowered the slip dramatically and picked up 5-7mph instantly, for about 5 miles until the nearly brand new XR ate itself. This was with about 730hp@82mph.

I would start with some prop testing and then move on to spacers 1/2" at a time. Some times it doesn't take much.

Putting the prop deeper will get it to cleaner water and allow it to carry the bow better due to more bite and leverage.
My 28 Pantera had a notched transom and was cut at 20.5 and had a 2" spacer, making the PS depth the same as an 18.5. Slip% was high like yours and trim had little effect on trying to raise the bow. I changed to a 3" spacer and prop slip went down about 7-8% and responded to trim much better. Being you have a steeped hull, your boat is designed to run flatter, but you still only want about a foot of water contact in front of the step.

BTW, I also had nose cone originally and considered that might be part of the problem. I switched to a DWP lower and did not see any significant change..

Ok I’m following you now. Really wish I had a video of it WOT to see the hull in action.

I called Hydromotive today and picked up a P5X at their recommendation. Todd there suggested a 24p. He suggested to prop it 1k RPM over peak torque, which was at 4700, so potentially 5700 at WOT.

They didn’t have a LH in stock, so he’s going to ship my a 24p RH to test knowing I’ll either send it back for a 24 LH or try a different prop. Their 30 day prop trial is pretty nice. I know BBlades offers a similar program. I did try to call Brett, but it sounded like he’s way behind on following up with customers. Figured this would be a good start to see how it responds.

Next step will be adjustments to drive height, but just maybe I’ll get lucky with a prop.