30 Spectre I/O porpoise

[Brad Zastrow]

My friend bought a 30 Spectre with twin 525SC with bravos.
He has been having a really bad porpoise problem with the boat. I offered to get in the boat and help him with driving it and maybe try to lick this. He has four blade bravos.
I drove the boat and nothing worked to stop the hop. I tried gentle arcs and then straighten the boat out ...hop, hop.
Here is what I noticed. Neutral and slightly negative trim the boat was a little better but would not air out and get to the speed where it would stop the porpoise. Anything over neutral trim and the drives would blow out and the bow would fall even more. I think his drives are too high or he need to try five blade props. Maybe both. I did forget to ask if he is turning props in or out.
Anybody with similar issues on the Spectre 30?

[fast fun 2]

Most of them have the 60-75 mph small pourpoise..but a small chop or a little more speed fixes it.

[Brad Zastrow]

This is not like any cat I have driven before. Can NOT drive through it. Another man was with us who had owned a 30 Spectre with I/O was really puzzeled as well. He said his was never like this. The owner has prior cat ownership as well. I have owned 10. Never anything this bad. I know we can fix it. Anybody try five blade props? How about propshaft heights?

[MDGperformance]

What style lower unit does it have?I owned a couple of 30 spectres one had hp500 ran hydromotive quad 4 with hydromotive nose cones a little hop 70-80,now the first one i had ran 502-450 (1996) installed warlock performance nose cones,similar to imco hopped all over the place out of control,tried all sorts of props no 5blades back then,no luck ended up installing lower units with no nose cones boat ran fine some hop in mid range but would set at around 80-85,also put some weight in the nose

[fast fun 2]

I dont know what year he started, but I know Jay layed sand up with the resin in the bow of 30 ios.

[obrien]

even if you put imco 2" shorties on the 30, you wont be able to get the drives too high. We played around on a 30 mounting the drives and engines as high as we could. The boat was running a pair of 500 efi's with imco 2" shorties, back when imco was just coming out with those lowers. We saw 111 mph when a hose blew from too much water pressure.

If you measure prop shaft hieghts, they should come out about 1.5 - 2" below the running surface. I know the 36 ran the best with the prop shafts 1.5" above the running surface.

I would take a good look at the lowers, and if they have nose cones, check to make sure they are straight.

All the 30 i/o's that were built when I was there had sand bags glassed in the bow.

Another thought could be the extra weight of the blowers on the old 525 sc's. That might be just enough to piss it off.

[fast fun 2]

I always thought a 30 with hot SBCs would be a cool package

[seltzer]

According to the original owner of my boat (whats up Sonny) My boat picked up 10 mph when he changed to 2 in" sportmasters. Mine hops between 65 and 85 in calm water. If the wind is blowing there is very little hop. I dont know if the 2 in" sportmaster helped or not with the hop.
Ive always been told the 30 and 36's have a hop, but the 32's dont.

[obrien]

If I remember correctly sunny's boat ran 115 or close to it. We build his boat with the drives about as high as we could possibly get them, plus adding the shorties. I wish his 36 ran alittle better though.

[Boater8987]

Same here in my 36. Porpoise 65 to 90 then sets.