Permatrim Options

[poly]

some of the members may be aware that i fitted a peratrim to the poly to help overcome a problem with porpoising at w.o.t. although it fixed the that one it has coursed others,such as with the motor trimmed wright in when coming out of the hole the boat will do a sudden and uncontrolled turn to starboard and can only be stopped by shutting down the power, this can be over come by trimming the motor out by 5 degrease from vertical and she will kick out strait and true.
my question is this would a 4 blade prop be better as i have been told they give good stern lift and better trim control but will cost top end speed.

[Spudly]

I think the initial problem is easier to deal with by adjusting the height/trim of the motor?

Ya know ya wouldnt have these problems with a ALLOY BOAT!!

[SUMOFISHIN]

Poly, this is a problem I had with the big boat, I tried different props and it did the same, pull to the right was hard to control so I always lifted the trim as I was accelerating and never had problems, it's just a matter of getting used to the modification: I think that some of these cavitation plates are a bit too big.

[nimrod]

some of the members may be aware that i fitted a peratrim to the poly to help overcome a problem with porpoising at w.o.t. although it fixed the that one it has coursed others,such as with the motor trimmed wright in when coming out of the hole the boat will do a sudden and uncontrolled turn to starboard and can only be stopped by shutting down the power, this can be over come by trimming the motor out by 5 degrease from vertical and she will kick out strait and true.
my question is this would a 4 blade prop be better as i have been told they give good stern lift and better trim control but will cost top end speed.

Poly. If I had of seen the post where you was asking about fitting a permatrim or not, I would have advised you to find the cause of the boat porposing in the first place and fix the problem, rather then fitting the cause of other problems.
All I can suggest now is that you take the trim thing off and find the cause why your boat does not perform to the standards it should have been built to.
To suggest anything else would be like a dog chasing it's tail.
Frank

This post has been edited by nimrod: Feb 2 2008, 03:01 PM

[SUMOFISHIN]

Poly , come to think of it I had that porpoising Problem with the new GOZO boat, I lifted the motor an inch on the transom and it fixed the problem

[Jumpus GooDarus]

I was never convinced the permatrims were a good thingy even though I'd read how some peeps swear by them.

Hadyou mentioned it down the coast I would've had a good look @ the way the motor was set up & yep how a motor is set up will play a roll in how the boat performs.

such as with the motor trimmed wright in when coming out of the hole the boat will do a sudden and uncontrolled turn to starboard

Being a tiller steer which side of the boat is all the weight on ?? people on board are deemed as weight.

my question is this would a 4 blade prop be better as i have been told they give good stern lift and better trim control but will cost top end speed.

I'd look @ finding the cause B4 spending more money on band aid solutions

[poly]

Being a tiller steer which side of the boat is all the weight on ?? people on board are deemed as weight.

i am well aware of the weight redistribution and i have that well worked out.

I think the initial problem is easier to deal with by adjusting the height/trim of the motor?

yep have dune that rum, when the motor was fist fitted it was to low and created a lot of drag so was lifted one hole and it made a big difference to how she preformed but that is when the porpoising started, so it has me stuffed :o :o :o

[Spudly]

can you move your trim pin on the engine down to trim the nose down more?? My first choice!
is the prop cavitating at all?
Can you lift the engine higher again (if not cavitating already?)


If all else fails,
The Yamaha probably has to much power, Might have to trade it in on an Etec or somthing!!

[poly]

can you move your trim pin on the engine down to trim the nose down more?? My first choice!

she is fitted with p t&t rum, and yes i do think it is some how related to the trim of the boat

is the prop cavitating at all?

yes but only in very tight turns even with the motor trimmed in it will cavitate but is great in a strait line or gentle turn

when i picked the boat up after the motor was adjusted i was not talking to the mechanic that did the job so there may have been some miss communication along the way and the motor lifted 2 holes in stead of one

[Jumpus GooDarus]

poly I thought you got power tilt & trim with your new 4 banger ????

Now I'll see if I can explain what you've done so far so as you can understand

Porpoising

Well that is a balance issue & it was something you complained about with the last motor, you have to remember your boat is a tiller steer so the bulk of the weight is aft & it cant be balanced out by having possum sit up on the bow add to that the extra weight of the 4 banger you have now.

I think you can avoid the porpoising by going into a gradual acceleration having said that I haven't been in your boat to see 1st hand.


Now you tell us you've added a pematrim & the boat is listing starboard well of course that will happen if you've accelerated to fast & the permatrim will enhance the listing.

What you need to remember is that every boat has it's limitations & you as the driver must know them & thats what makes for safe boating instead of gunning the motor off the start gradually build up the speed & you'll find you'll subdue the probs you're having adding a 4 blade or any other device is not the answer.

Give you an example on my wittle boat being so light I have to position where I want the crew to sit when driving her @ speed else she dosn't perform even drifting or on anchor if there's someone on board who's got a bit of weight on them is moving around I feel the boat want to play silly buggers that's why I only like 2 on board.

Not making fun of him & only using it as an example but some time back SUMO was on the wittle boat now SUMO weigh's more than double what I do & evertime he moved I felt the boat shift aware of the weight I only motored out @ 1/2 thoatle & when it started pissing down rain & we did the bolta to get back in I really felt the boat slideing from under me & it did list going side on into the wind.

Mainly because I got SUMO to go stand central & aft & brought this point up simply because all the weight in your boat is aft

Now had you gone into a centre or side consol when you got the 4 banger instead of tiller steer I think all your probs would've been sorted out.

Next time out try gradually building up speed & come back & tell us if you're getting the same probs

[Spudly]

when you say porposing, you mean the bow is constantly doing the ups and downs (like the old skua's)

even with power trim there should still be a pin that sets where the lowest trim is. Im sure thy still have that??? Try lowering that pin to let the motor trim down more..

Otherwise, stick a pair of thongs under there and enjoy the ride

[Jumpus GooDarus]

Otherwise, stick a pair of thongs under there and enjoy the ride

Hmm ! wouldn't be a pretty sight Rum seeing poly wearing a thong

[poly]

thanks for that j g,now to explain my way of coming on to the plain, fist my understanding of the correct way to do this [ with the motor trimmed wright in start accelerating slowly adding up trim and power till the boat levels out then adjust trim to suit condition's] is that wright.

now to the way i have to get her up and out of the hole [ trim motor to about 5 degrease out from vertical apply power as she comes out and accelerating and lifting apply some down trim till she levels out then trim to condition's and then bring revs up to cursing speed] at no time do i snap the throttle open.
lets see if we can get this one sorted out fist and then move on to the next question.

[Spudly]

I think yas all play with yaselves, I mean trims to much... Once you find a good point for it you should rarly have to adjust... xcpt for changing conditions ie, chop etc..

You definatly shouldnt have to be worrying about adjusting you trim on the take off though.. You should be able to control this by the amount of throttle..

Just rmember having trim is an extra and many smaller engines are only just getting it so how did we survive before it.. By having the motor balenced correctly..

All boats lift the nose on the take off.. I have always found that a quick burst of power to get boat quickly on plane and then back off t a suitable speed work the best, and that goes for tinnys with 15hp right through to ski boats.

[poly]

Just rmember having trim is an extra and many smaller engines are only just getting it so how did we survive before it.. By having the motor balenced correctly..

i didn't have it on the thirty rum but when i got it on the 40, i have no idea how i lived with out it, it makes a lot or difference to the way u can get the boat to perform.

[Spudly]

thats true poly, but you should have to be constantly adjusting it, specially not just for take off... Sure its great to be able to raise the nose in a bit of chop or even when going flat out for that extra bit of speed, but you shouldnt have to be using it to improve yuor take off and you should be able to trim the nose down enough to stop it lifting.

I woould be checking there isnt a pin that stops it dropping right down..

[poly]

of course u are wright rum, but i must refer u back to my fist post with the motor trimmed wright in the boat will just do a u turn, not good i can tell u, now she only dose this coming out of the hole, with the boat trimmed in to a chop there is no sign of it

there is a stop fitted to the bottom hole to stop the motor from going in any further. hope this helps

[poly]

Poly. If I had of seen the post where you was asking about fitting a permatrim or not, I would have advised you to find the cause of the boat porposing in the first place and fix the problem, rather then fitting the cause of other problems.
All I can suggest now is that you take the trim thing off and find the cause why your boat does not perform to the standards it should have been built to.
To suggest anything else would be like a dog chasing it's tail.
Frank

i have done that twice frank to try and find it, i have added weight in the form of sand bags to the bow for a little improvement but not a lot so mate any thing u or the others can come up with i will try :o :o :o

[Spudly]

lend me the boat for a few months poly and ill sort it out for ya!!

[poly]

lend me the boat for a few months poly and ill sort it out for ya!!

couldn't do that rum u would become a plastic nut just like me, next thing u know u would be out playing in a 3mt tuff tender with 10hp doing laps around all the tinny's

just like this bloke

http://www.youtube.com/watch?v=busnD8e6aBg




This post has been edited by poly: Feb 2 2008, 09:20 PM