hey mate noelms right not worth the stress you are going through i dont even look at my trim guages its all by feel.
wayne
hey mate noelms right not worth the stress you are going through i dont even look at my trim guages its all by feel.
wayne
GT
Have you tried toe-out as a contrast to your present set up?
You do need to "feel" what the boat is doing so as others have said the guages perhaps should only be the 'indicators" at the beginning of each assessment run.
Experience from others is as below
"Toe in to me means the nosecone of the gearboxes are closer together and the exhaut hubs further apart. That is props are angles outwards.
Toe out is obviously the reverse.
Have found that very little is best for a start and that on high speed running on flat water you can get more porpoiseing with toe out but a more stable lateral ride when not hammering at top speed .
Slight Toe in- is more predictable offshore and stops the boat trying to turn ( tip sponson in ) when running along swells on your beam"
Cheers
Chimo
What could go wrong.......................
Yeah Like Noelm and Kitty cat said is correct, I have never looked at my trim gauges ever either, just trim to suit the speed/conditions, even a quick glance at the motors gives you an idea what the hull should or will be doing. Sounds like you need more practice!!
thanks to all-- much appreciated everyones input ,experience and advice -- a lot more help than the builder!! a few more things to take on board and try . as I have said I have'nt had much time on cats -- the last 15 years on mono's -- med to large platey's so it's all been a steep learning curve on the cat . cheers
I'm assuming that when you are trying to trim the boat you are triming the Port engine out & the Starboard engine in ? This may sound back-to-front ,but this is how cats work . By trimming in, it lifts the transome on that side up thus the whole hull. By trimming out, it forces the transome down along with that hull.
Try a bit of negative trim on your Starboard side & some positive trim on your Port side. Once you have the boat sitting level then you can adjust your overall trim like a mono by trimming both engines at the same time- trim out to lift the nose of the boat or trim in to lower the nose.
You may already know all of this - just thought i would mention this incase you are getting all crossed up.
Laraby
Buy a mono hullOriginally Posted by gtphantom
On a serious note this is not uncommon on cats, particularly narrow beam ones such as the Leasurecats. I use (but don't own) a 7m L/cat which has recently been repowered with 150 suzukis. I never noticed this before with the 140s it had but then it would only top 28 knots, now it gets to 38 kts but the stbd bow digs in at more than 30kts. It gets a bit hairy at the higher speeds & I have tried all sorts of trim settings to no avail. Now I'm thinking it's the narrow beam that may be the cause.
how old is the 7m you got? was that you that Leisurecat gave you the advice about the props and trimming a couple weeks ago?
Can I guess you guys are running bladed props?
don't understand the question ?
Sorry didn't have number lock on on the keyoard
It should have read 4 bladed props? .
In some hulls the extra lift they create mean the hulls at the rear are not "settled "in the water well at high speed. The back walks about making it feel out of balance.
Well set up a boat and good hull design shouldn't rely or need a prop that lifts the transom and the power can be better used pushing rather than lifting. Interesting to hear if someone has had this hull at even higher speed and how it performed. A lot of issues that are minor at usual speeds get very serious at higher speeds although that is not what it is designed for.
What props have been tried and what difference have any of them made?
G'day fellas -- have already measured the cav plate hieght at parralell to the keel-- both are within 1-2mm of each other , acceptable i would think? We have tried with three sets of props , the set supplied from Suzuki, 14" dia 20"pitch , solas 14' dia 21" pitch -- both three blades ,and 13 7/8"dia 21" pitch solas four blades . The four blades seem to be a lot better but still tends to want to lift the port hull. The thrust tabs have been all over the place with setting ,initially they were set at dead astern -- how they came out of the box , L/C want the port tab set at full port and the starb on full starb ? After I've done some test and recording all this seems to do is take up-to 3knts off at different RPM's can't see any advantage the best I've had it is with the four blade props and the thrust/trim tabs removed -- at the minute I've got the 21" pitch solas three blade on with flat tabs and the limiting bar on the PTT to stop the leg going into to much reverse trim- this combination seems not to bad but as I said before I seem to only have a very small margin of positive trim before the props cavitate
the steering is hydrive units with the cat valve -- I've bled the system thoroghly and have nice smooth steering -- I hav'nt had to reset the hydraulic line valve since the initial install and the O/B's have about 10-15mm toe-in this hasn't altered and Iv'e not had to top up the fluid level-- no obvious leaks
both O/Bs are getting the right WOT@ 5900-6000rpm
trimming the O/B's independantly in or out isn't succesfull cos it cavitates
when the PTT is on the limiting bar both trim gauges read the same
Have you tried toe out of at least 15 mm?
Cheers
Chimo
OK . Is it the whole hull , sponson that feels like it is lifting or are you referring to the bow lifting higher on the port side?
Just trying to clarify what you mean.
If sitting at rest is the boat level?
Hpw much tilt are we talking about and are you noticing it as you see the bow rail against the horizon or is it just the brain and eyes?
My last suggestion is that the limit pins are possibly allowing no negative trim ( some boat sellers set it up like that so people don't get into nasty trouble in following seas) and for whatever reason on the plane the trim needs to be negative rather than trimmed out. Triming - if port hull bow is lifting then 2 choices. Trim out port motor or trim in starboard motor. Yep it is the opposide to what you think as other have said.
Not sure if your motors are set back from the trailing edge of the transom but for every 6 inches a 1 inch rise in the cav plate approx is the norm to have the motors at the right height. If too heigh you may get constant airation of prop as you try and trim out.
Chimos toe out is how I have set em up before as well.
LC suggestions of tabs goes against everything I know. They only exist to stop torque steer. With hydraulic set up or a tiebar they are not really required but some will like them to take the weight off the steering rams and the main steering bearing and so if you have a tie bar failure a motor will still point straight ahead.
the faster you travel the more the port hull rises -- the crew has also commented and it feels as though it will go over in conditions we were ski buisciting!!
as far a neg trim I have none at all with the limit pins in and as I said before , only limited pos trim -- this isn't how L/C set it up
you were towing a ski buscuit with a 18' cat ????????????? are you allowing for driver weight ? is the ski buscuit tied to the starboard side of the hull ??
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