New to me 21' Xtreme Cat

**BigCanadianGuy** · 07-03-2019, 09:13 PM

Hey Guys!

I just picked up a 21' Xtreme cat with a 300x on the back. Hydraulic jack plate, 28p 4 blade lab matched prop. 202 hrs. Boat runs great. I've owned lots of boats that have gotten into the 90's but never a cat. Hoping someone out there might be able to help with a couple of questions.

1st is, when it comes out of the hole, it immediately planes out on the left sponson and at about 30 mph sits flat and rides smooth. Why does it hop out onto the left sponson first?

2nd, I'm well aware that a cat will require a certain amount of air to get it smoothed out at speed. I'm having difficulty in both with and against the wind on very smooth days on the lake keeping the boat from porposing between 58-70mph. It will porpose and then begins to rotational porpose. No matter what trim setting I have it at, I can't seem to get past that point. I don't want to push it too far yet because I'm still getting used to the boat obviously. I had mild wind conditions yesterday and Into the wind I finally got enough air under it and it planted itself in the water up to 87mph with lots of throttle left, but with boat traffic approaching, I let off at that point.

Any help would be appreciated. Thank you! Safe boating out there!

**JPEROG** · 07-03-2019, 09:54 PM

Your right hand propeller rotation will push the left side of the boat down on acceleration. It will always favor one side until the hull gets some lift under it-if you are turning to the left as you come on plane it will favor to the right.
As for your porpoise, almost every true tunnel will have a transition stage of needing to pack air in order to lift and perform correctly. This can be at lower speeds if the weight is less and it will move to a higher range with a heavier load. The best way to avoid it is to turn the boat into a right hand arch as you accelerate and run past the transition stage with strong throttle application so that you don't allow the hull time to start a rhythmic hop. Once you master it, you will forget that it has the hop until you try to cruise within the transition zone-you just can't do it without a center pod and there will always be a "no fly zone".

Joe

**BigCanadianGuy** · 07-03-2019, 10:07 PM

Thanks Joe, I appreciate the help. I knew I would have to push past the hop, and once it gets past it it rides like a cat should. Solid. The right hand Arch is a great tip, I'll give that a shot tomorrow. Cheers

**home made tunnel** · 07-03-2019, 11:33 PM

Originally Posted by JPEROG

Your right hand propeller rotation will push the left side of the boat down on acceleration. It will always favor one side until the hull gets some lift under it-if you are turning to the left as you come on plane it favor to the right.
As for you porpoise, almost every true tunnel will have a transition stage of needing to pack air in order to lift and perform correctly. This can be at lower speeds if the weight is less and it will move to a higher range with a heavier load. The best way to avoid it is to turn the boat into a right hand arch as you accelerate and run past the transition stage with strong throttle application so that you don't allow the hull time to start a rhythmic hop. Once you master it, you will forget that it has the hop until you try to cruise within the transition zone-you just can't do it without a center pod and there will always be a "no fly zone".

Joe

This even helps me - As I have the same exact things (albeit more extreme) with my mini tunnel. I know I still need more bow weight and less stern weight, but yes, Same issues!
The OP stated the symptoms the best... Getting on plane, it leans way Left... Hit the gas, she flattens out. Right hand turn, she leans WAY left. Left hand turn - not so much, but some right lean.
And if I stay in the porpoise, it does also start to barrel roll a bit.

So you're saying, before you get into the hop zone, turn slight right to avoid it?

**home made tunnel** · 07-03-2019, 11:34 PM

BigCanadianGuy - - - Here's my post of my porpoising haha. I'm sure its a little more extreme than yours:
https://www.screamandfly.com/showthr...nel-Hull-Video

**BigCanadianGuy** · 07-03-2019, 11:38 PM

Hahaha maybe a bit..

**BigCanadianGuy** · 07-04-2019, 10:11 AM

So today we'll go for the techniques suggested by JPEROG and see about getting over the hop with much more ease. Hope you have a safe and happy 4th of July!!

On a side note, do you think that rigging the boat with twins and a tunnel tab would make that hop almost dissapear? If you went with twin 225's and wanted to cruise in that 60-70mph range (which is where I like to limit it on my busy lake some days) and then when you get out into open water you'd have massive acceleration and fun top speeds, wouldn't that be the best of both worlds? I wouldn't do that yet, I still like the challenge of figuring out a new toy, but for the future that might be something to consider. Thoughts?

**Euroski** · 07-04-2019, 10:34 AM

Just like the 21 Skater I had on both issues. On smooth water a very slight steering left and right(S turn) helps with the porpoise, but runs best with rougher water. I would usually cruise about 75-80.

**Captaincj** · 07-05-2019, 11:48 AM

Originally Posted by BigCanadianGuy

So today we'll go for the techniques suggested by JPEROG and see about getting over the hop with much more ease. Hope you have a safe and happy 4th of July!!

On a side note, do you think that rigging the boat with twins and a tunnel tab would make that hop almost dissapear? If you went with twin 225's and wanted to cruise in that 60-70mph range (which is where I like to limit it on my busy lake some days) and then when you get out into open water you'd have massive acceleration and fun top speeds, wouldn't that be the best of both worlds? I wouldn't do that yet, I still like the challenge of figuring out a new toy, but for the future that might be something to consider. Thoughts?

I owned a 21 skater with twin 200's years ago (basically same(ish) hull I think). After learning to drive it I almost didn't have a "hop some" anymore, or could power through it. Had amazing acceleration with twins. Ran cleavers. Calm water was more "hop prone". Preferred some light to moderate chop.

**JPEROG** · 07-05-2019, 12:00 PM

Originally Posted by BigCanadianGuy

So today we'll go for the techniques suggested by JPEROG and see about getting over the hop with much more ease. Hope you have a safe and happy 4th of July!!

On a side note, do you think that rigging the boat with twins and a tunnel tab would make that hop almost dissapear? If you went with twin 225's and wanted to cruise in that 60-70mph range (which is where I like to limit it on my busy lake some days) and then when you get out into open water you'd have massive acceleration and fun top speeds, wouldn't that be the best of both worlds? I wouldn't do that yet, I still like the challenge of figuring out a new toy, but for the future that might be something to consider. Thoughts?

Twins on a 21 are not the answer for cruising (you still have to make turns). They are a blast straight line acceleration but the hop isn't better with two motors (you can through it faster) but the handling and general usability gets worse as an overall.

A center tab is great way to control the hop but is very stressful on the transom (you are working directly against what the boat is wanting to do every-time its down). The other negative about a tab is that they can trip the boat (cause it to stuff) when making a re-entry. The most important thing is that with twins on a 21, you have enough going on that you will forget to bring the tab back up at some point (anybody that has one and says that they have never done it is a lair) and when it happens, you are in for a one scary ride at best case scenario.

When you are done with this one move up to a 24' skater or 28' DW if the water you run on is big enough for a larger boat.

A twin boat is almost always "safer to me" due to the fact that you have a 2nd motor that is neutralizing/equalizing all of the bad things that a single does". I don't think that I would make that statement about a 21' after being in few of them.

Joe

**Captaincj** · 07-05-2019, 12:08 PM

Originally Posted by JPEROG

Twins on a 21 are not the answer for cruising (you still have to make turns). They are a blast straight line acceleration but the hop isn't better with two motors (you can through it faster) but the handling and general usability gets worse as an overall.

A center tab is great way to control the hop but is very stressful on the transom (you are working directly against what the boat is wanting to do every-time its down). The other negative about a tab is that they can trip the boat (cause it to stuff) when making a re-entry. The most important thing is that with twins on a 21, you have enough going on that you will forget to bring the tab back up at some point (anybody that has one and says that they have never done it is a lair) and when it happens, you are in for a one scary ride at best case scenario.

When you are done with this one move up to a 24' skater or 28' DW is the water your run on is big enough.

A twin boat is almost always "safer to me" due to the fact that you have a 2nd motor that is neutralizing/equalizing all of the bad things that a single does". I don't think that I would make that statement about a 21' after being in few of them.

Joe

You have WAY more experience than me, but I absolutely LOVED my 21 skater with twin 200's.

I remember when first getting to know the boat it had hop problems, but eventually I knew the trim settings and throttle needed to keep it from hopping and loved everything about the boat.

But I may have had a really dialed in boat from previous owner.

**JPEROG** · 07-05-2019, 12:21 PM

Originally Posted by Captaincj

You have WAY more experience than me, but I absolutely LOVED my 21 skater with twin 200's.

I remember when first getting to know the boat it had hop problems, but eventually I knew the trim settings and throttle needed to keep it from hopping and loved everything about the boat.

But I may have had a really dialed in boat from previous owner.

Didn't say that they were not fun or that they weren't usable for sure. Just overall handling general usability is not as good one with a strong single. I had a triple engine 24' skater and the same differences apply to it "a blast but only for the acceleration factor over a good twin boat".

Joe

**Captaincj** · 07-05-2019, 12:23 PM

I hear ya. I was really happy with the handling also, but never drove one with a good single to know how much better it could be...

**Jamescole** · 07-05-2019, 12:27 PM

Originally Posted by BigCanadianGuy

Thanks Joe, I appreciate the help. I knew I would have to push past the hop, and once it gets past it it rides like a cat should. Solid. The right hand Arch is a great tip, I'll give that a shot tomorrow. Cheers

I recently picked up a 21 Skater and i have tried 3-4 props and every prop changes the hop dramatically. i find a bone stock bravo 1 takes my hop from 50-72 mph to 50-64mph. makes for nice cruising conditions just under 70. also i dont have to turn as hard to stop it from bouncing.... only a slight turn will do the trick.

**BigCanadianGuy** · 07-05-2019, 03:43 PM

I totally agree about twins. I have always wanted a twin cat, specially a 24' skater, but I kissed one earlier and found this one with a pretty good deal. I have plenty of big water out in Georgian bay and my lake has enough water to handle a 24' boat for sure. Thank you for all the input! I'm having a great time slowly learning my new cat and will eventually upgrade when I've had enough time with it. I really appreciate the comments. Keep em coming if you have more to give! Cheers, and enjoy that sunny weather!