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.

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!!

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.

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

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

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.



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



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

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



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

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!!

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



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

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

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

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

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.

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.

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.

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..

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

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

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

Rumpus there's 3 thingys you never ask a man to lend you

1. His Car
2. His Boat
3. His Bum

poly trim is only there to fine tune the performance nothing more & yes the motor needs to be tilted in all the way [this is a genaral comment not all boats are set up the same way]

It's no good having your motor trimed up when you take off as the prop wont bite in as well as it will struggle to lift the boats nose up.

Once you're under way that's when you do a slight trim of your motor & I stress trim not tilt by that I mean dont go overboard else you'll start hearing the motor reving out to much & if you hit a bump in the water you will cavitate.

When triming I do it by ear you get to know when your motor is reving just right prob not what you wanted to hear as it dosen't explain alot to you but yep I do it by ear

Well i was gonna borrow your "Ute" to tow it and i thought Poly's were differant to boats?

Id rather have nothing to do with any of your bums!!!

not having a trim gauge i have to do the same, when i say the motor has to be trimmed out at 5 degrease from the vertical that is an estimate on my part it may be a bit more or less but that is the only way i can get it out of the hole safely.

Well looks like every one has had their say. If it was me Pol I would get in contact with the people who sold and installed the motor and tell them to sort it out. They would not like it if you started telling others of how they never set up your boat properly in the first palce. But you must give them a chance to rectify the fault first. If they don't ............ DFT Department of Fair Trading just love to deal with people who don't hold up to their end of the bargin.

The guys who fit the motor can only do it one way Arnie & that's Central with the Motors Cav Plate flush with bottom of the boats V not much else they can do.

They didn't sell poly the boat just the motor & as long as the motor performs then thats all they are liable for.

Boats aren't like cars each boat is generally fitted to owners specs & the people who sold the motor to poly cant be held responsible for the boats layout or performance.

Poly is best off asking @ the polycraft site he visits if anybody else has had the probs he's had to deal with.

Comments by myself & others here are only general refering to boats in general

Thanks for that i thought they were all in kahoots

is a Permatrim a brand of hyrofoil cause i been looking at getting one

Why, what is your boat not doing correctly ?.
Frank

i would say stay away from them S C i don't think they are worth the trouble, and yes they are a type of hydrofoil.

Poly if I run into you again there's a few wittle thingy's I can get you to try to rule out this & that
They're a bit hard to convey in a thread & I need to be on the boat to see for myself

southcoastin !

If your boat is performing why would you bother adding something that is not required ???

Personally I'm not a big fan of foils some peeps rave on about them but I dont really think they know what they're on about

well i had a long talk with a good friend of mine who has had many years in the marine industry, i told him of my problem with the boat trying to do a u turn as i accelerate out of the hole and he suggested that the motor was most likely trimming in to far and trying to berry the nose, and i should move the stop pin out one hole at a time till the problem disappeared if that did not work he would call in next time he was down and sort it out for me.
so i took the boat down to the river this afternoon to give it a try, after moving the stop pin out 2 holes the boat was running strait and true and since the permatrim has fixed the porpoising problem i will leave it alone

POLY,
Maybe now that you have the pulling problem fixed, it probably wouldn't hurt to undo the permatrim (it's only four little bolts) and see how the boat performs without it ,
You never know, it could be better

sumo the the problem only happened coming out of the hole once on the plan she ran strait so i am going to leave well enough alone as the boat is now preforming well

S. C. listen to the advise that J.G. and i have given u if there is a problem with your boat please post it and the members will try to nut it out for u, any thing u add to the motor that is below the water line will rob u of top end speed, in the case of the permatrim on my boat its about 5kmsph so think carefully before fitting one, as u can see it coursed me a head ache and a half

Good to see you get it sorted poly.

Made for an interesting topic to read also.

thanks J.G. for offer but as u can see i have it sorted, but the day may still come when i can take u for a ride in my little boat



thanks mate it sure had me scratching my head.



this is something i though about , but this being what i call my home site and with the wisdom of the members here this is the best place to get the help i needed, if dave had not phoned to say he was coming down I AM SURE that one of the members would have come up with the fix

Think Rumpus suggested you do that early in the thread poly.

Yep Yep if motor is trimed to far in it's not so much a case of the nose burying itself in quite the opposite actually.

What does happen though is that the motor is trying to get the nose up to quick which in turn can bury the nose off to one side & that's what I think was happening to you.

Again I was not there to see what was going on & my comments are in theory only.

bringing an old topic back from the death i know!!!!

But for 4 years ive always wondered what my boat would handle like without the permatrim that came fitted to it..

Finally i pulled it off and give it a go. After the first run i was defiantly going to put it back on. after the second run i cant believe i took the boat out again without it..

I never had any issues with the permatrim, boat handled fantastic, but was just interested to try..

Things i noticed immediately were;

* boat was much slower to get onto plane. this became even worse when i loaded 4 adults onto boat. now its only a 5.4m boat and has the max HP (130hp 2 stroke) allowed but i do have some weight in the rear in 130lt fuel and 2 batteries and a live well..

* Even with the motor fully trimmed down i could not bring the nose down. this became much worse going into any swell as the boat launched of the waves and was consistent at any speed. the only time the boat really flattened out was at 4000rpm or greater on flat water.

* Now i know someone is going to say I need more negative trim here but there is plenty, believe me, so much so that the motor looks odd fully trimmed down and the steering becomes unbelievably heavy, an issue Ive never before had..

So what i have found with the permatrim installed on my boat!

Much greater control of engine trim / boat relations. I can lift or drop the nose easily.
Much greater take offs, quicker and without the bow lifting.
much much much lighter steering!

I really cant see any reason not to have it on there!

Im sure i could try more things like moving batteries and weight forward, negative trim packing under the engine, hydralic steering (for tight steering) but why would you stuff around with any of that when a boat handles perfectly well with a simple permatrim added.

Thought it is worth sharing my experiance for anyone else going through the same process!

for anyone reading who doesnt know, boat is a haines signature 540f with yamaha 130hp.

It Just Goes to show that if you do some experimenting you will solve problems, Diagnosis is something that you can use with all problems especially Motor Vehicles.

I suppose it's good to get another view and opinion on these things.
You have used the boat with the trim on for a while with no apparent issues and now you have tried it with the trim off and found it's not to your liking.
Whatever works for you I spose that's how you have to go.
Personally I don't believe they are needed on trailer sized boats, on larger boats you use trim tabs, same issues you are bandaiding the original problem,
the problem is still there you have just counteracted the problem so it's no longer an obvious problem.
A lot of people confuse porposing with natural wave motion, and think because the boat is moving in a up and down motion that it is porposing.

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