Zodiac Splitting transom at engine bolts - advise needed please - Page 3

Tims Osprey · 26 June 2007, 00:13

Whats a searider

Nos4r2 · 26 June 2007, 00:15

Quote:

Originally Posted by Tims Osprey

Whats a searider

Oh, come on... I'm not going to have to use the sarcasm detector on an Osprey owner am I?

jwalker · 26 June 2007, 01:52

I don't know your engine but it occured to me that if the tilt and trim system was filled with fluid while the engine was in the lift position, there would become a fluid block at some point as the engine is lowered because there would be no place for the excess fluid to go. When you solve the trim hydraulics problem, the position of the trim stop rod is important because it prevents the engine being trimmed in too far. Trimming in too far can produce severe steering behaviour, which could eject you from the boat, so it's worth going gently while determining the bar's position.

Lowering your engine is straightforward. Since you will need to destroy your lower engine bolts to slacken them, replace them first but leave them slightly loose. Place a block of wood and a jack under the skeg of the engine, remove the top bolts and lower the engine until the desired top holes line up with the holes in the transom and then replace the top bolts. Remembering about fully tightening the lower ones too.

I wouldn't adjust the engine height until the trim problem is sorted. The height may prove to be correct.

I don't know why your transom has cracked but my guess is that the transom construction is hollow and it only has an infill in the area of the engine mountings. If the transom flexed under load, which I would expect it to do, there will be a load on the join of the inner and outer transom faces and that join looks to be a simple butt joint and it's not able to withstand the load. For a proper fix you need to remove the engine. There are various ways to repair it depending on the lengths you are prepared to go to. Just filling it with gel resin is not a satisfactory solution.

All imho, of course.

Hugh Jardon · 26 June 2007, 07:26

hopefully yours hasnt but have a good look over the engine mounting and all the metal work structure for the engine.

i had a honda 90 and a dealer said they are prone to cracking around the mounting supports etc, mine was ok but have a good look over yours just to be on the safe side.

IBWET · 26 June 2007, 08:33

Quote:

Originally Posted by mhb100

Hi Nos,

yep, but they dont appear to be moving enough - ill have another look tomorrow. I've never checked the fluids as i assumed they have during servicing so it probably a good idea to check ...

Mark

Just a thought,

my engine has an overtilt device,(so you can't trim to engine out to far) it's adjustable by the owner, is there any chance honda have one of these for avoiding timming in beyond a certain point ?

chris t · 26 June 2007, 19:55

I have a split in the same place as you on my zodiac 4.2 ive just put gel coat on it and check it each time and hope the the outboard doesnt fall off.

mhb100 · 26 June 2007, 22:23

Good news, sorted the trim out - nothing wrong with it i just stopped it early when a nosie started assuming that was as far as it would go - as opposed to letting it go all the way (so im a donkey!) but it does seem noisey

now that i have trimmed down I can confirm that the cavitational plate and the hull are aligned - basically the hull is only about 10mm lower - so i beleive this is fine - if i dropped the engine then it would end up about 10mm lower than the hull which I'm guessing is the worst option ?

I'm really glad about this and it makes sense as the boat does drive ok, always seems to trim out ok, but just seems to vent during manouvres more than i'd expect.

SO I DONT NEED TO MOVE THE ENGINE DOWN !!!!

I have also got hold of the original honda installation guidlines (so Nos im gonna PM you a copy) which seems to cover installation, size of prop, bolt torques, etc. I cant make sense of it yet but it will confirm (i think) if the props right or not, and if the bolts were too tight contributing to the crack!. It does state that top bolt holes should not be within 1" of the top of the transom - which this is not thankfully - but i cant imagine why a manufacture would only recommend 1" as this seems too little to me...

[Nos, if you get chance can you have a look at the stuff I'm sending you as it might help sort the props size - the last mechanical issue!]

I'm gonna plan to repair the fibreglass - I also like the idea of a plate - where could i get one made up from,do i need one inside and outside, and how would you seal it to the hull?

Cheers
Mark

mhb100 · 26 June 2007, 22:31

Quote:

Originally Posted by chris t

I have a split in the same place as you on my zodiac 4.2 ive just put gel coat on it and check it each time and hope the the outboard doesnt fall off.

Hi Chris

How long has the gel coat lasted?
have you had to keep repairing it or just the once?
did you notice if the transom was hollow behind the crack and if so did you fill this with anything?

thanks Mark

chris t · 26 June 2007, 22:38

Quote:

Originally Posted by mhb100

Hi Chris

How long has the gel coat lasted?
have you had to keep repairing it or just the once?
did you notice if the transom was hollow behind the crack and if so did you fill this with anything?

thanks Mark

I think we put some gel coat on it about 3 months ago and so far it is still ok and has no cracks.
sorry can't remeber if it was hollow or not, we just pushed the gel coat in until no more would fit.

mhb100 · 27 June 2007, 14:31

Hi Guys

thanks for the info about by zodiac transom issue. Looks like the trim/tile and engine height is ok so its a case that its poor design,etc

Like the idea of a transom plate - has any one done this?

currently the engine sits on a plywood pad. I assume I would remove this and fit over the plate or just discard it completely?

do you know where I can get them made up at a reasonable cost?

and how do you fix/seal these to the transom; apart from the 4 engine bolts?

any information appreciated as i need to get this ordered asap

thanks
Mark

Chris · 01 July 2007, 14:09

Mark what shaft length is the Honda? (sorry if this has been asked b4)

Chris

bedajim · 01 July 2007, 15:29

Quote:

Originally Posted by mhb100

Hi Guys

thanks for the info about by zodiac transom issue. Looks like the trim/tile and engine height is ok so its a case that its poor design,etc

Like the idea of a transom plate - has any one done this?

currently the engine sits on a plywood pad. I assume I would remove this and fit over the plate or just discard it completely?

do you know where I can get them made up at a reasonable cost?

and how do you fix/seal these to the transom; apart from the 4 engine bolts?

any information appreciated as i need to get this ordered asap

thanks
Mark

Hi

I would lift the engine off clean out the cracks and fill with gelcoat and make a new spacer out of marine ply(sealed with gelcoat) or plastic to clear the lip at the top of the transom then have a stainless steel plate folded up to go over the transom like an upside down U section then bolt the engine back on.
If you make a patern out of carboard for the outside and the inside of the transom with top edge as a datum line you can mark the holes for mounting the out board(if you have 12 mm bolts i'd have 16 mm holes put in so that you can easily mount the outboard and get plenty of sikaflex in). take these to a metal fab shop and get them to make it up, you'll have to tell them the back to front dimension of the transom so they can bend the U section to fit +1 mm on the inside dimension like the pictures i posted here

http://rib.net/forum/showthread.php?t=20173&page=3

But thats just what i'd do

James

mhb100 · 01 July 2007, 18:20

Quote:

Originally Posted by Chris1573

Mark what shaft length is the Honda? (sorry if this has been asked b4)

Chris

Hi Chirs

Long shaft,

mhb100 · 01 July 2007, 18:22

Quote:

Originally Posted by bedajim

Hi

I would lift the engine off clean out the cracks and fill with gelcoat and make a new spacer out of marine ply(sealed with gelcoat) or plastic to clear the lip at the top of the transom then have a stainless steel plate folded up to go over the transom like an upside down U section then bolt the engine back on.
If you make a patern out of carboard for the outside and the inside of the transom with top edge as a datum line you can mark the holes for mounting the out board(if you have 12 mm bolts i'd have 16 mm holes put in so that you can easily mount the outboard and get plenty of sikaflex in). take these to a metal fab shop and get them to make it up, you'll have to tell them the back to front dimension of the transom so they can bend the U section to fit +1 mm on the inside dimension like the pictures i posted here

http://rib.net/forum/showthread.php?t=20173&page=3

But thats just what i'd do

James

Hi James, thanks for this, very helpful
Mark

Chris · 01 July 2007, 21:59

SO therein lies the problem your transom height (21") is designed to take a short shaft and the guys that rigged the boat clearly had a longshaft in stock so made it fit by fitting it too high on the transom.

Thats a bit shite really.

Sorry if this has already been covered.

Chris

mhb100 · 01 July 2007, 22:02

Guys,

Looks like the issue with the zodiac transom might not be what it appears.

First of all i'm gonna to put the issue of engine position on the transom to bed

......The zodiac has a lowish transom and the honda (long) is also longer than most at 537mm; compared to say a Suzuki 4 stroke which i now know to be 508mm. The saddle cannot sit on the transom without putting the cavitational plate several inches below the hull. I guess in 1999 there were not many 4 strokes to choose from!. I have dropped the engine 1 bolt hole so its just inline with the hull as opposed to 1" above as it might assist with the cavitation i get when turning. Having spoken to many dealers and mechanical engineers whilst it is more common for engine saddles to sit on the transom there is no reason for it to as the 4 engine bolts are more than adequate to take the load and distrube it. The bottom line is that most do sit on the top of the transom; or very near to it because the engine length dictates it.. moral seems to be choose the ideal engine length for your transom then you'll get the best of both worlds so a 508mm seems best for the Zodiac Pro Open

The failing transom....Good news.

After investigation today I now know there is no damage to the structural part of the transom. The spliting is not on the main transom but where the top and hull moulds join together. The split runs parallel to this seam - there is no splitting elsewhere, and having moved the engine today and checked all bolt holes,etc im pretty sure of that.

Having done a postmortum on the cracks (with a grinder) its clear to see whats gone on. On top of the solid transom (where the lip is) is actually a hollow box section (yes hollow,what a design!) the top is about 3-4mm thick the rear about 20mm and the front (where the cracks appeared) about 5mm. In between all this is a hollow core section running the length of the transom. The join where the cracks appeared seem to have the least silkaflex or similar bonding the join. Remedy seems to be to fill with epoxy and finish in gel coat. If the crack had been anywhere else then the outcome would have been very different! . I will look at a transom plate as well.

only remaining issue is the weight of the engine exceeding the transom weight. Still working on this. If the insurance dont have an issue then ill keep it; if not its engine exchange time......

M

mhb100 · 01 July 2007, 22:05

PS forgot to say thanks Nos for your help - really appreciated mate

Nos4r2 · 01 July 2007, 22:54

Anytime mate

prairie tuber · 02 July 2007, 04:07

I'd always thought a longshaft was a longshaft was a longshaft but 537mm vs. 508mm is more than an inch difference. What the boat manufacturers should do is have an integrated transom height extension system where you can add in a factory designed integrated extension piece for the particular outboard you opt for so that the saddle of the bracket can sit directly on the transom.

It would seem to me that having the bracket saddle resting directly on the transom along with 4 bolts, will disperse stress alot more effectively than 4 bolts only would.

mhb100 · 02 July 2007, 12:40

Hi,

I think the zodiac pro open (in my year) may be the exception to the rule about 4 bolts versus resting ontop of transom.

The bottom line is that the top part of the transom is a hollow box section. So in this design the solid transom part is where the 4 bolts are. I'm not sure on this model I would want the shoulder taking the weight!

Zodiac did beef the transom up since 1999; whilst I dont know what mods they have done, they have increased the transom max by about 30kg. I can't even seem to find out if the transom top was supposed to be solid ( and therefore a fault in production) or not in the first place. It just seems rather a strange design.

Good news is that is that its worked fine for 8 years and theres lots of these rib/honda packages out there......

M