Re: 259 Convincor w/ 600hp
 

I have the same problem in our 2000 259. What prop are you running? We have a Mirage Plus 23P 3 blade. The porposing is obnoxious when the boat is full of people. I have been told a 4 blade prop will help. I really enjoy the ride of our boat beyond 4000RPM and some positive trim, carries the bow well. However getting there is not fun when there are four people sitting in the back seat. I am curious to hear other comments on this problem by Checkmate owners. I have tried all sorts of drive positions and tab positions, so I believe it is just a handling characteristic of the hull design and not user error.

Re: 259 Convincor w/ 600hp
 

My '99 259 has the same ride characteristics at slow speed. I have the same problem when my wife comes with me. She is only comfortable going slower. Of course, then she complains about the propoising. If I run anywhere below about 40 mph, it will do it. While attempting to maximize speed, I have run several props. None of which helped the porpoising. The only thing I found was to bury those stock junk Insta-Trim tabs. 2 years ago, I switched to Dana Marine hp-1000 tabs. Now the porpoising goes away with a little down tab, about #4 on my mechanical indicator. BTW, I am running a 25" P-5X for a prop.

Re: 259 Convincor w/ 600hp
 

I have the same boat and it does the same thing. There is a thread that I started about (why does a boat porpose) in the general threads. There is some good info there.

Russ

Re: 259 Convincor w/ 600hp
 

I run 380 tabs and that alone will stop the problem. Then again I never cruise under 55mph. Thats only 3000rpm for me. Below that I'm wasting fuel. BTW I'm running a 5 blade with a 2" shorty, but if you have stock power 5 blades are not the best for you.

Bottom line- get better tabs and a 4 blade bravo 1 prop.

Re: 259 Convincor w/ 600hp
 

Dave,
That is because your wife is not a sissy like mine. Did you see that Sonic?? I didnt know you got the shorty back on.

Re: 259 Convincor w/ 600hp
 

You need to pick them young, my wife was 17 when we met. Now she loves speed.

What Sonic???

The shorty lower was back to me in 10 days, Bmax takes care of me. But it may blow again, I just raised the boost... Again. 17Ibs now! I'm not advertising the top speed any more.

Re: 259 Convincor w/ 600hp
 

here's the link

Re: 259 Convincor w/ 600hp
 

I thought you told me that you were running with a twin engine Sonic last weekend. Or maybe it was a Scarab?

Re: 259 Convincor w/ 600hp
 

Scarab.

The weather did not cooperate. But I WILL see him before the end of the summer.

Re: 259 Convincor w/ 600hp
 

For best performance you should not keep the same prop on that you use for top speed when you put a load of people in a 25’ Checkmate….Prop it to run close to max rpms at WOT for the load you have. Actually, I get lazy and leave my speed prop on, and I can still control the porpoising down to about 3000, 3200-3400 for sure, with 4 people. Russ G is probably getting sick of my saying that, but it is controllable down under 4000 with trim and throttle work. I rarely use my tabs unless I’m running thru some nasty stuff. Under 3000 and it’s very difficult to stop or controll. Just the way the hull is, it has a fast cruising speed and is an excellent top end runner.

-Craig