Trying to get a little more speed with tabs and hydrofoil

[bruceb58]

Re: Trying to get a little more speed with tabs and hydrofoil

http://www.fquick.com/garages/viewgallery.php?albumid=3&carid=27298&page=1.

I guess you had foam. Did you take it all out?

 

[aerobat]

Re: Trying to get a little more speed with tabs and hydrofoil

like mentioned your rpm,s are a little low and you are wasting horses since the engine is not yet on its peak power output at this rpm. i also quess a 19pitch three blade will bring you to the correct WOT rpm,s and ~45mph when you now reach 42 . beyond that the question is - can we expect more than rougly 45mph from the good old 5.7 carbed v8 and a 22 cabin footer. ?

i think any information that the engine ever reved out a 23pitch prop and hit 55mph at this boat is chairman talking. so i think nothing is wrong with your engine and it gives that power you can expect from a carbed 5.7 , not more not less.

cheers !

 

[Mike Zee]

Re: Trying to get a little more speed with tabs and hydrofoil

You can do all kind of tuning up, that's not a bad thing. But you will most likley end up with a good running boat, that won't go any faster than you do now. I still vote for a prop change. Only because of the specs of your prop(s). Put a 14x19 3b of any material on and all things being equal she will feel like a different boat. I put the 14.5x19 4b (from iboats) because it was on sale. What I needed to buy was the 14x18. I knew it but I went cheap, now my boat runs out the same as OP's. It would do 48 with my dinged up 14x19 3b, but I put spare on until I sprung for the 4b. Now my target prop is a 14x18 stainless 4b. This was my experience from last year, take it for what it's worth.

 

[2ndtry]

Re: Trying to get a little more speed with tabs and hydrofoil

Looks like you removed foam, was it wet? If so I bet there is more on the other side :O

BTW is the first pic in your album Beaufort inlet?

 

[geneseo1911]

Re: Trying to get a little more speed with tabs and hydrofoil

You have a 350 in a 19' bowrider?

I do....
It's an '82 Cobalt.....big & heavy, very deep V. Made for bigger water than I will ever have it in. I'm a Chevy guy, so when I found this with the small block in it, I jumped. There's something "right" about having the same motor in you boat and your pickup. The problem is I just bought an 8.1L Suburban....

 

[jumpjets]

Re: Trying to get a little more speed with tabs and hydrofoil

I removed all the foam that was exposed underneath the hole I cut in the deck. The bottom areas of the foam had some moisture, but not much. The top of the foam was dry. The deck and stringer wood was damp, so I just kept cutting until I found dry wood. I replaced all the wet wood that was exposed with dry wood.

I'm willing to bet there is a gallon or two of water hiding elsewhere underneath the deck of the boat, but I don't think it's "waterlogged".

I pulled the distributor cap off a while back (to take the pictures I posted). I bet I put it back in in a disoriented fashion so that the timing is a few degrees less.

3 more weeks until I can dig into it and check everything out.

 

[chriscraft254]

Re: Trying to get a little more speed with tabs and hydrofoil

I have a 22' wellcraft cuddy with a 5.7 merc and alpha one. Currently, it tops out at 42mph at about 4000rpm. I'm thinking of doing some upgrades to improve speed and efficiency.

1. Smart Tabs SX: these look like they would do exactly what I wanted. They aren't expensive either. I'm super nervous about drilling into my transom though, especially below the water line. I'm also worried that once I drill into the transom, I might find wet wood. That would ruin my day. The boat is holding together just fine, and I don't want to ruin my summer by finding out I have a soggy transom.

Don't worry about drilling the holes, if its wet, you can dry the holes out before install of the tabs. If you install the smart tabs, 5200 to holes before installing the screws. This can be done even on a wet transom. Get the stainless smart tabs. there the way to go for your boat imo. They will increase all aspects of your performance and you WILL gain speed if it is similar to my experience. I gained 4 to 5. You will be astonished at the other benifits these tabs bring to your boat.

Here is a link to a thread I started to explain my experience with Nauticus tabs and to find out what others have experienced. May help you make a decision on wether you want them or not. http://forums.iboats.com/showthread.php?t=520309&highlight=smart+tabs

2. Hydrofoil: These are very cheap, and I imagine that they would aid in stability and planing. The smart tab page says specifically not to install any other planing device with smart tabs installed. Does this mean I can't install a hydrofoil with smart tabs? What would happen if I did?

You do not want a hydrofoil installed with any trim tabs installed. The nauticus tabs adjust to water pressure. If you have a foil installed it can effect the performance of the tabs, plus hydrofoils are not adjustable. Smart tabs self adjust to gain performance. Don't waste your money on a hydrofoil. Nauticus is making tabs for boats up to 30 feet now and your size boat they will be great on. You can take a look at my refurb thread and see the install on mine.

3. New prop: I have a 4 blade aluminum 19 pitch prop. I think if I installed a 4 blade stainless steel 17 pitch prop, that would put the boat right into the engines power band of 4200-4600rpm, instead of down at 4000rpm where it is now. It would also keep the boat from bogging so badly when I had a full load of 6 people on board.

Prop and motor definately should be figured out before tabs are installed so you can see and feel the difference when they are.

 

[jumpjets]

Re: Trying to get a little more speed with tabs and hydrofoil

Looks like you removed foam, was it wet? If so I bet there is more on the other side :O

BTW is the first pic in your album Beaufort inlet?

It's 20 miles north of Beaufort inlet.

UPDATE!:

I have returned to the United States. I got my boat out of storage and dewinterized it. The mechanics who stored it said it was in great working order, and that he could not find any "rot". The transom is dry, and the deck is solid. There "could" be some moisture under the deck though. I don't know.

It has new spark plugs, and I put a new ACCEL coil on as well. With 50% fuel (25 gal), and two adults on board, I got 45.3mph at 4200rpm using a garmin GPS. I had a moderate (50lbs) of junk on board, and the river had light chop, about 6" waves.

I still intend the weigh the boat as soon as I can, and check the timing.

Sadly, I hit a fat rock at the end of my trip, and I bent one blade of my prop and bent the fin on the bottom of the outdrive. I'll try to straighten the scag, but I might need a new prop.

 

[bekosh]

Re: Trying to get a little more speed with tabs and hydrofoil

It's a 3300 lb (dry weight) boat with 260 HP.

If she were a 60+ MPH boat, I'd guess she'd be wearing a 23p, 3-blade SS prop out of the factory. I don't think that's a 60 MPH boat by any means.

I had the same boat with a 7.4l/Bravo 1 (1.5 ratio), and she'd run 60 (alright 59.2:redface at 4800-4900rpms with a 21p Mercury Mirage+ prop. With the 5.7l there no way she'll run 60 even though the hull is good for it.

If she were a 50 MPH boat, I'd guess she'd be wearing a 21p, 3-blade SS prop out of the factory. I do think that's a 50 MPH boat, give or take a few MPH. If me instincts is wrong, I'll lick the 19p prop she might have been wearin' out of the factory to hit 45+. However, this is the bottom of the acceptable prop pitch range I can imagine.

We are now talking about going down to a 17p prop?! Yikes! Get yer calcs out, boys 'n' girls, because that screams trouble to me.

I agree, she should run 50~ish with the 5.7l, but I would put my money on a 19p Mirage+ for speed. The Mirage+ has a good amount of cup on the tip and enough rake to carry the bow high which this hull seems to like. I tried several other brands and the Mirage+ worked the best for me.

It's 20 miles north of Beaufort inlet.

UPDATE!:

I have returned to the United States. I got my boat out of storage and dewinterized it. The mechanics who stored it said it was in great working order, and that he could not find any "rot". The transom is dry, and the deck is solid. There "could" be some moisture under the deck though. I don't know.

It has new spark plugs, and I put a new ACCEL coil on as well. With 50% fuel (25 gal), and two adults on board, I got 45.3mph at 4200rpm using a garmin GPS. I had a moderate (50lbs) of junk on board, and the river had light chop, about 6" waves.

I still intend the weigh the boat as soon as I can, and check the timing.

Sadly, I hit a fat rock at the end of my trip, and I bent one blade of my prop and bent the fin on the bottom of the outdrive. I'll try to straighten the scag, but I might need a new prop.

I think your rpms are still low. IIRC you should be 4400-4800 with that motor. Which should get you about 50 with a 19p prop. You can run your numbers here http://www.go-fast.com/Prop_Slip_Calculator.htm
The Eclipse will never be a true speed demon, too deep a V for that. But she'll chew through 1-3 footers without breaking a sweat.

 

[H20Rat]

Re: Trying to get a little more speed with tabs and hydrofoil

Sorry it's 8.34 lbs/gallon

depends...

Cold seawater with a high salt content can be heavier than 8.6 lb/gallon. The water in your hottub at 104 degrees is less than 8.3 lb/gallon. Typical lakewater is going to be somewhere in between, obviously much closer to 8.3.

 

[Oshkosh1]

Re: Trying to get a little more speed with tabs and hydrofoil

Ditch the Al prop...
A 19P SS should be the ticket.

Keep the RPMS up at the higher end, that motor can easily take it!

 

[lugster84]

Re: Trying to get a little more speed with tabs and hydrofoil

I had the same issues with a 19' regal (89 4.3l) that gathered similar responses. I was advised by a mechanic that I only use every couple of years that the transom could be bad from sitting in the water all season etc. Then he said don't freak out, when is the last time it was tuned up (by him, it was at least 2 years). He stated to bring it to him he tunes dozens a week, I tune once every 3 years with back yard tools. Long story short the boat is back to performing 42 mph around 4k rpm (SS 3 blade stiletto) (I cleaned the hull extensively), I love my boat again, can't wait for this weekend to put it in, got a boat lift to not worry about the transom (or sinking which it almost did years ago) and in the process of installing nauticus smart tabs sx which a buddy of mine with the same boat said did wonders. Good luck and thanks for serving!

 

[jumpjets]

Re: Trying to get a little more speed with tabs and hydrofoil

It's been a few months since this thread died, but I finally got around to weighing the boat.

My full rig tipped the scales at 9660 lbs.
My exploder and trailer were 5980 lbs.
Which means the boat itself is 3680 lbs.

The boat is listed with a dry weight of 3300 lbs. I had a hair under a half tank of fuel. It's a 53gal tank, and I'd bet I had ~23gal. At 6lbs/gal, that's 138lbs of fuel. I also had just pulled it out of the water, so there was surely some residual water in the cooling system, a wet anchor rope, and just a touch of sea spray on the whole boat. I also had roughly 100lbs of random stuff, like a took box, a tube, some first aid supplies, etc..

I honestly can't judge if the boat is waterlogged or not. It 400lbs above dry weight average for this size boat?

Also, throughout the summer, the boat has been topping out at around 45mph and between 4000-4150rpm. Thats too low, so I'm going to shoot the timing soon.

 

[TilliamWe]

Re: Trying to get a little more speed with tabs and hydrofoil

No, that weight isn't too high. Published weights on boats are usually low, anyway. Yours isn't water logged to any extent.

So you've either got an engine issue or prop issue.

 

[bruceb58]

Re: Trying to get a little more speed with tabs and hydrofoil

I would be surprised if your boat has any or much foam in it since it is over 20' long.