Need Help!! 22' Scarab with 280Merc with Planing Issue

[TilliamWe]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Does that motor say 280 horsepower on it somewhere? I wasn't aware Mercruiser had a 280hp carbureted motor then. In 1996 the 5.7LX EFI Gen+ was 280hp. That's a Vortec engine. The carbed engine was usually rated at 260hp.

 

['78 Crusader]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Sounds like a classic example of being over-propped. Your set up for top end speed, not bottom end performance. Like others have said, try some lower pitched props. You may give up some top end speed but you'll gain bottom end performance.

Also....might want to look into Smart Tabs too.

 

[chris50smith]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Does that motor say 280 horsepower on it somewhere? I wasn't aware Mercruiser had a 280hp carbureted motor then. In 1996 the 5.7LX EFI Gen+ was 280hp. That's a Vortec engine. The carbed engine was usually rated at 260hp.

You are correct. It is the 260MERC

 

[chris50smith]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Sounds like a classic example of being over-propped. Your set up for top end speed, not bottom end performance. Like others have said, try some lower pitched props. You may give up some top end speed but you'll gain bottom end performance.

Also....might want to look into Smart Tabs too.

Went to Complete Marine in Phoenix today. After mentioning to their head mechanic, he does not think it is a spun hub. he agrees with you. He thinks I am overpropped for that big of a load. He said either increase horsepower or go to a 19" or 20" prop. He didnt look at the prop yet, but he is betting I have a 22" prop on the boat. We shall see. I like the 55-60MPH speed of the boat, but want to make sure we get on plane in a decent amount of time.

Maybe I will just turbo charge the motor (half kidding of course)

The mechanic also recommended either adding a "whale tail" to the outdrive, or adding some trim tabs. When you say smart tabs, are they the kind that do not require any wiring? Let me know. Thanks!

 

[nikon]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Dunno if the same will apply to you, but....I had to rebuild my trim rams, while doing so the instructions said there was a 'washer' in there that limited how far down the drive could trim down (93' alpha 1 gen II) I took those washers out and it really, I mean REALLY helped my hole shot...you do have to remember to trim up as shes coming up on plane though or it will plow really bad....my boat is fairly similar to yours 20' wellcraft with a 350 mag, same seating configuration....if I have full fuel/gear (beer) and 6 people on board I still have to have 1-2 people come forward by the windshield to get on plane in a decent time....but 5 people and full tank of fuel, no one has to get up from their seats, she planes off nicely.....I too do about 55-60 wide open....

If I hadn't done that I would have bought trim tabs.

Heres a shot of my boat, I'm guessing it's pretty similar to yours.

 

[NSBCraig]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

No to whale tail!

Check offshore only.com and screama and fly.com.

 

[chris50smith]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Dunno if the same will apply to you, but....I had to rebuild my trim rams, while doing so the instructions said there was a 'washer' in there that limited how far down the drive could trim down (93' alpha 1 gen II) I took those washers out and it really, I mean REALLY helped my hole shot...you do have to remember to trim up as shes coming up on plane though or it will plow really bad....my boat is fairly similar to yours 20' wellcraft with a 350 mag, same seating configuration....if I have full fuel/gear (beer) and 6 people on board I still have to have 1-2 people come forward by the windshield to get on plane in a decent time....but 5 people and full tank of fuel, no one has to get up from their seats, she planes off nicely.....I too do about 55-60 wide open....

If I hadn't done that I would have bought trim tabs.

Heres a shot of my boat, I'm guessing it's pretty similar to yours.

Yes, very similar boat. I am going to play with it on the next trip. I think I might add trim tabs just for fun too!!! The boat mechanic says that I can add a "whale tail" to the outdrive, since it is the biggest "bang for my buck" and YES, people standing up and moving forward works too. Thanks!

 

['78 Crusader]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Don't add a WHALE TAIL!! That will slow you down as they will add a lot of drag. Do the right thing and get the proper prop on her.

 

[nikon]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Ya, skip the whale tail.....btw you don't have to spend any money to remove the washer/spacer from the trim rams, just remove the caps of the rams, slide em out remove the spacer, re-install and prime the system.

 

[AZBoatDreamer]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

How was the Customer Service at complet marine. I only had my boat for a Year and I want to have someone do basic service and I haven't been to a Marine shop Yet.

I mentioned Spun Hub just to rule it out even though it was most likey not the cause. Just wondering if your prop was slipping in the Hub.

OK the next few sentences may be pointless.

55-60mph top End Speed. Whats your hurry. Just sucking up GAS. Most of my Cruise is at 25- 30 mph.

I like have Quick Planning out of the Hole for Water Sports.

I haven't even tried WOT on my Boat but it plans in seconds. Never had a need to go faster than 30mph.

 

[1979checkmate]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

you gotta get the kicks of going wide open once in a while!

 

[AZBoatDreamer]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

And Scare the Wife and Kids.

 

[nikon]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

you gotta get the kicks of going wide open once in a while!

Hell ya.

I'd be happier at 90+

 

[ChampionShip]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Whale tail is helpful for keeping your boat on plane at lower speeds for better fuel economy (mostly) while it does help with a bit of transom lift and easier planing and hole shot you'll be better served by buying a spare prop (3 blade might not be a bad idea) for when you have it loaded heavy, and keep your top end prop for light loads. It only takes a minute to change them out, may as well just do that.

 

[TilliamWe]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

Actually Champion, a three blade prop is probably a worse idea for when it's loaded heavy. Think High Five or a lower pitched 4 blade.
Whale tail is the worst idea anyone could come up with.

 

[QC]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

OMG, the variety of stuff in this thread . . .

1) If you are really turning 4800 RPM you are NOT overpropped. Check tach for accuracy.

2) You put a Whale Tail on a 55 MPH boat and I will personally meet you at Havasu and take it off

3) Yes, trim tabs, they solve the poor planing/high speed boat issue without eating up that same top speed. Go Bennet's or Lencos or other helm adjustable tabs.

4) Check speed with GPS. Small block carbed and 55 MPH are rare no matter what the size of boat. True 22 footer, VERY rare.

5) This one I will defer to actual experience, I've heard it before, but I cannot believe there is ever a spun hub and also 50+ MPH. Makes no sense to me. A spun hub locks up under the heaviest load?

 

[DaNinja]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

OMG, the variety of stuff in this thread . . .

1) If you are really turning 4800 RPM you are NOT overpropped. Check tach for accuracy.

2) You put a Whale Tail on a 55 MPH boat and I will personally meet you at Havasu and take it off

3) Yes, trim tabs, they solve the poor planing/high speed boat issue without eating up that same top speed. Go Bennet's or Lencos or other helm adjustable tabs.

4) Check speed with GPS. Small block carbed and 55 MPH are rare no matter what the size of boat. True 22 footer, VERY rare.

5) This one I will defer to actual experience, I've heard it before, but I cannot believe there is ever a spun hub and also 50+ MPH. Makes no sense to me. A spun hub locks up under the heaviest load?

I agree with all but #4, QC.

I've seen 53 mph on the 24' Deckboat with just me and <half-tank of gas. GPS confirmed, but that was propped pretty tall.

The 21' SeaRay that I grew up with would do 65ish, but that wasn't a pure stock 350 and there wasn't GPS back then.

Our BR200 is reported to be able to do nearly 60 mph, but I won't fall on my sword on that one. The SeaRay is propped pretty tall, but that was after a mechanic's lake test and they had an interest in selling me on the work that they had done.

 

[QC]

Re: Need Help!! 22' Scarab with 280Merc with Planing Issue

I agree with all but #4, QC.

Yeah, it was a pretty bold statement, but I stand pretty close to behind it. There are exceptions for sure. I had a 1995 5.7 in a 20 footer and almost touched 60, but some clarifications are in order. The standard carbed 5.7 was rated only 235 at the popshaft (260 at the flywheel) there was no "260" then. The TBI that I had was rated 250 at the propshaft, and this boat was less than 16 degrees of deadrise (like your deckboat) and again, only 20 ft.

Also . . . I have a small block now. 6.2 320 propshaft in a 23 footer and she tickles 57. But that's 85 more ponies, hence my comments.

Here's my old 20 footer, and loaded up barely 55 . . . and again that was 250 propshaft: