kevla Cat Trimming

[saltiga]

Hi every one I own a 5.2 meyer kevla cat tournament with 90 two stroke mercs I seem to be working all the time to keep it trimmed to stop it leaning from port to starboard and starboard to port has any one fitted foils to there cats or does any one have any other ideas.

[Noelm]

foils are a mixed bag, most hate them (me) and some like them, remember when up and running on the plane, they are out of the water (or should be) can you better explain your problem, if you mean rocking from side to side when under way, then that is a 5.2 "feature" that is not often spoken about, but if you are describing something different, then give us a better idea, also remember that the trim affects the Boat diagonally, like the Port side Motor if trimmed up/out will lift the starboard bow, if you get what I mean.

[saltiga]

Thanks noelm your on the right track i have one motor trimmed slightly higher than the other when under way to keep the boat level but slight changes in conditions or movement in the boat changes the level and i always seem to be trying to trimm up or down to keep it level.

[Stuart]

I know exactly what you mean. Foils won’t fix the problem at all mate. In fact I haven’t seen any foils of any make or model on the back of a 5.2 Kevla Cat. I have spent hundreds of hours behind the wheel of this model and I know what your experiencing and it can fixed with the press of one button. When underway and the sea is rolling in and hitting you on your port side, trim your port engine up until the is stays more level. The same goes for the Starboard side. Don’t trim the engines so high that they begin to cavitate. But you do want the engine up a fair way. What happens is the boat wants to roll but the engine looses grip or lift and the boat comes back down, it stays at that level the whole time while travelling in that direction.


The same when travelling with the sea, if the sea is rolling in and hitting you quarter on at say the port side then you trim your port engine up until the action stops or at least reduces dramatically. This will come with practice but this will point you in the right direction. You should have this mastered in say a few trips, you will feal the boat change and that’s how you learn to drive a cat. Driving a Cat is all about feel, it may sound hairy fairy but I can assure you that’s what you do, feel what the boat is doing and trim it to suite.

Stu

[Barraholic]

As a recently joined member of the 5.2 kevlacat owners' club, I am currently going through the same process. I have found the cross lateral trim characteristic as Noelm was referring to takes some playing with on an ongoing basis as you drive the boat. Even if you change direction marginally to a sea you need to adjust the trim on one of the motors to level things up. I imagine this will come more naturally as experience grows.

You can even pre-adjust for a turn as you enter it, i.e right hand down then starboard motor slight trim up or port motor slight trim down. Trim it back when you are out of the turn and slightly adjust for the changed direction to the sea. The guy who I bought the boat off had mentioned how he used to adjust for a turn into a swell coming out of his protected waters from his local port.

As has been mentioned if one motor is starting the cavitate then trim it down and use the other motor to adjust (i.e. trimming the non-cavitating motor down will have the same affect as trimming the cavitating motor out). I might be imagining things but there seems to be a sweet spot when the motors relative trim to each other is just right.

The other thing I have noticed is that the impact in trim changes comes more significant depending on the revs you are doing. I've noticed going at full noise (yee har!!) the trim adjustments needed are less to give the same effect - interested in more experienced owners' view on this.

One of the more experienced guys on this forum via PM had mentioned to me that one time you may need to trim in rather than trimming out is in a big following sea to minimise the boat bogging down.

One other thing I had picked up from theses forums is about not turning away from a "hole" that appears in front of you - imagine it is on your port side, and if you try to turn to starboard you are going to exaggerate the "drop" on the port sponson (i.e. lean out effect plus depth of "hole"). If you turn into the hole the port side will effectively lift and then its own bouyancy/dynamic lift will drive it to counter act the drop from the "hole" i.e it will "pop out" of the hole.

One thing to remember at the end of the day, all boats no matter how well they are designed or how big they are are a floating vessel on a dynamic moving mass of water so you are never going to completely eliminate rocking/movement.

Interested in more experienced ausfish 5.2 KC owner's (I know who you are ;) ) comments on any other tricks to driving these great boats to their fullest potenital. I know I am in love with the way it handles and all the guys who have been out in it are blown away by how it handles and the fact that it on paper it is classed as a 17 foot boat.

Hope this helps,

Kev

[saltiga]

Thanks Stu when i am travelling I have one motor trimmed higher than the other to keep the cat level is this normal I presume this is to counter act the boat not haveing counter rotating props I also crossed the wake of another boat travelling parralel with the other boat one hull seemed to dig in and how hard can you turn a kevla cat its a little bit daunting at the moment

[saltiga]

Thanks kev I am happy with the Kc and would also be interested in any comments or ideas from other owners with more hours up than me I think my problem is me not knowing how far I can push the boat.

[finding_time]

Saltiga

i'm not going to tell you how far you can push it , you'll work out your own limits ;) but by way of an example i drove into a VERY big hole of the goldy recently in really sh!thouse conditions and the starboard side staino rail was under water!!!:o

I think the boat will go further than you will be prepared to push it! i know i never want to put myself in that position again! One of my crew members was thinking about swimming home after all we were only 25nm offshore!;D