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Discussion Starter #1
I drove a 25 Daytona today. Had a blown BBC in it. I had a porpoise at around 70, is that normal? The who owns it said it will do 95mph with the weight bag, and over 100 without it.

The guy had 240 lbs in the front of it for weight. Why would one do that on a 25? Are these that flighty that weight is needed?
 

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mach26 300's
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at around 70 most cats will start to porpoise since there on the edge of packing that good air so yes it is very normal. you have to just drive through the porpoise especially if you have lots of weight towards the back such as people. the weight bag has nothing to do with that boat being flighty, there is no way that thing is gonna blow over even over 100. The bag probably helps the porpoise or plane faster, based on his preference on how he uses the boat.

I drove a 25 Daytona today. Had a blown BBC in it. I had a porpoise at around 70, is that normal? The who owns it said it will do 95mph with the weight bag, and over 100 without it.

The guy had 240 lbs in the front of it for weight. Why would one do that on a 25? Are these that flighty that weight is needed?
 

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Havasu & Anaheim Hills
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The weight bag is not a good idea, if you want a boat that jumps up on plane by a jet, or change the prop to something small. Cats are not designed to pop up on plane, if he was struggling to get the boat on plane, it was a prop issue.

My 27 makes about 6 bounces at 80 and then flattens out from there on up. Its normal.
 

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The weight bag is not a good idea, if you want a boat that jumps up on plane by a jet, or change the prop to something small. Cats are not designed to pop up on plane, if he was struggling to get the boat on plane, it was a prop issue.

My 27 makes about 6 bounces at 80 and then flattens out from there on up. Its normal.
yep that about right. or drive height?;)
 

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Discussion Starter #8
I bought the boat today, so first thing I'm taking out the extra weight in the front.

Also the drive seems to be several inches below the transom.
The top of the gimbel housing is about 3 inches lower than the rub rail.
What is the recommended prop shaft to transom depth?

Do trim tabs work? I have seen them mounted on a couple Daytonas
 

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Discussion Starter #10 (Edited)
IT's got a 540cid with a M3 procharger with 6 lbs of boost, intercooler. Dart block, all forged internals, Canfield 350 heads, lightning headers; 91 octane, 8.8/1 compression. Fairly mild setup from what could actually come from this engine.
Previous owner say it probably is 700 hp.

I drove the boat and it would accelerate to 70 quickly, then it would seem to hit a wall quickly, but the trim gage was not operable and I had no idea where the trim should be. I had a lot of down trim in it. It seem to have a lot more speed in it but my driving was probably the issue. I did not go any faster. The guy I bought it from said it would do 90 with all of us in it, but my wife was with me and I really did not want him to take it that fast with her in it.

It's got a 4 blade ss bravo 28 pitch prop. The drive is a 1.5/1 ratio.
At 70 I think it was around 4000 rpms if I remember correct.

It has the standard lower unit in it, not the CLE lower pickup unit.
Which brings me to another topic that Ill hit later.
 

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With 700 hp it should run deep in the 90's. You my be under propped. I have a 25 with a teague 800 and runs over 100 with full tanks and 4 people. Also running a 30 labbed Bravo with 1.36 gears. However the boat does plane slowly and I let it to save the drive.

Get some seat time before you start running hard. They are a drivers boat and will surprise you. They are weight sensative as with most cats and takes a while before you will know what it is going to do before it happens. I am still learning. Good luck. How about some pics!
 

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What sytle 25? Is the center sponson cut down flat about halfway back?

My ICC 25 will run over 90 with 625 hp any day. But you have to trim it up. I run about +5 on my bluewater trim gauge over 80mph. Once you trim that thing up its going to speed up a lot.
 

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Discussion Starter #13
I know I did not have it trimmed up very much when I floored it.

But one time while cruising around 50, I did trim it up to see what it would do and the rpms went up a few hundred like the prop was slipping a little; is that normal?

When you are talking about the center sponson cut about half way, I'm not sure I know what you mean. What should I look for?
 

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I've got a 97' 25 daytona. It's a single step hull. Has a hp 500. All single steps have a slight porpoise. Mine does, but only when the water is flat. Lil chop, and it goes away and rides awesome. Sounds like you'll have no problem powering through it. Have fun
 

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Yea the porpoise is normal on that boat, the 04 or new have the new bottom, my 27' never has any of it! Now my old 25' Motion did like mad! Drive threw it and turn just alittle to vent one side.
 

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Discussion Starter #18
Checked the center sponson today and the sponson looks the same from the beginning back to the transom.

 

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What sytle 25? Is the center sponson cut down flat about halfway back?

My ICC 25 will run over 90 with 625 hp any day. But you have to trim it up. I run about +5 on my bluewater trim gauge over 80mph. Once you trim that thing up its going to speed up a lot.
Sounds correct. I trim to +4 at higher speeds.
 

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For sure my 27' with 1,000HP runs over 120Mph, with people in the boat! :) :)Two steps in the out side sponsons and i belive one big step in the center. (might have to take a look at that again)
 
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