Hairline cracks in transom - help!

[Bobalong]

I own a 3.6m RIB which has a 25hp outboard. The engine is a 4-stroke with electric tilt/trim, thus it is right on the size and weight limit for the boat (82kg). The engine mounting plate is bolted through the transom in 4 places (top-right, top-left, bottom-right, bottom-left). The boat is about a year old, I have owned it from new, and the dealer supplied and installed the engine for me.

I have used the RIB for about 25 hours since purchase, of which maybe half has been on the plane, including on some slightly choppy sea with a few small "airborne moments". Today, having given the boat a good clean, I noticed some fine hairline cracks had formed in the gelcoat on the transom. I am rather concerned about these, hence this post!

If you are looking aft at the transom (i.e. from inside the boat), the transom is strengthened on each side by a box-section moulding coming up from the floor at an angle of about 30deg from horizontal, effectively joining the transom to the hull floor and acting as strengthening member. The cracks in the gelcoat are forming on the vertical intersections where the box-sections meet the transom. Also at the bottom of the transom there is a margarine tub sized recess for water to collect in, out of which water can exit the hull if the drain plug is unscrewed. A few hairline cracks in the gelcoat are visible where the transom meets the floor in the vicinity of the recess.

There are no similar cracks visible on the aft-side of the transom, although at the top-centre of the transom there is a slightly bigger crack running horizontally, where the top surface of the transom appears to have separated slightly from the rear surface of the transom.

Shortly after purchase I discovered that in the boat manual the stated engine weight limit was 65kg, although the dealer had supplied me with an 82kg engine. When I queried this he said the manual was wrong and sent me an updated manual with the weight limit raised to 82kg. Fair enough I thought! However, now I have seen the hairline cracks I am concerned that the engine really is too heavy for the boat and that the cracks in the gelcoat are possibly the first signs of overstress.

Has anyone on the forum seen this type of problem before? Also as I am not an expert in fibreglass, can anyone tell me if the hairline cracks in the gelcoat are just that, or are they a sign of some more serious damage underneath? I am rather concerned about it because if they get any worse I will have to invoke the 5-year warranty on the hull with the dealer, which could become difficult.

Thanks in advance for any advice.

[Rokraider]

Some photo's might help. What make of RIB is it?

[Bigmuz7]

Originally Posted by Bobalong

Has anyone on the forum seen this type of problem before? Also as I am not an expert in fibreglass, can anyone tell me if the hairline cracks in the gelcoat are just that, or are they a sign of some more serious damage underneath?

Welcome to Ribnet .. unfortunately in such a concerned circumstance .. there are plenty of threads here about this type of problem if you do a search .. not all end in tears .. pics are required for some views, but thats all theyll be.

Interesting to hear about your dealers change of literature, whats the outboard ?

[Fenlander]

As far as I can see the Excel website and all dealers selling this model still say max 65kg outboard. 82kg is quite heavy for a rib that only weights 115kg in total. Add in some shock loading from speed in a chop and the cracks might be expected.

I've had it before on older grp boats where the cracks just seemd to be an initial relief of stress and they never became more than the finest hairline.

On a boat still in warranty though I'd try a gentle approach to the dealer but not be amazed if he said it was just cosmetic.

[Doug Stormforce]

I am not saying you want them but hairine cracks are generally not a major problem. It is likely that they are only in the surface and the fibre glass layers underneath are OK.

However if it is in warranty get it back to the dealer and politely tell him you want it fixed.

As said above a few images would probably tell us more.

[Bobalong]

Right, having read a bit more on the forums about this problem, I can give some more information. The hairline cracks are where the knees join the transom. Pictures are as follows: overview of the transom looking aft, with problem areas circled in red; individual photos of the hairline cracks in the problem areas; photo of the cracks on the aft side of the transom; note that these cracks are on both sides, extending under the engine mounts but have yet to meet up in the centre.

Any thoughts/advice welcome!

[Doug Stormforce]

2 of those cracks look more than hairline, get it back to the dealer

[Poly]

Not looking good. What does the ce plate say about engine weight? Suspect trading standards might be interested in his approach to ce marking from what we've heard.

[Ian M]

Just a thought, as others have said take the rig back but do not hand over that 'updated' manual, copies yes, but hang on to the original. If it gets nasty you may need it.

[biffer]

my guess is, as that is an internal moulding it doesn't fit the external one exactly so it flex's a bit, that bit up round the engine i would think is the joint between them both

[Bigmuz7]

Originally Posted by biffer

my guess is, as that is an internal moulding it doesn't fit the external one exactly so it flex's a bit, that bit up round the engine i would think is the joint between them both

Which is the one that would concern me the most .. Its the one that suggests why all the others have appeared IMO .. definately something moving in there .. No question as others have said, its a back to dealer job .. how you handle the fact that he sanctioned a heavier engine is another matter, are you sure he specified the max engine size by weight rather than HP ? because this has lead to a lot of confusion due to 4 strokes being a lot heavier than 2's of the same HP ... and can you clarify that the paperwork he gave you is correct from the RIB manufacturer, and if it is, that this higher spec applies to your boat, ie, do you have an earlier production model that shouldnt have had the heavier engine ?

[HUMBER P4VWL]

That last photo looks bad. Even if he says it is cosmetic, it isn't good enough.

If that is in warranty. Take it back and get it fixed at minimum.
If the engine is overweight for the transom, ask for a refund or replacement boat with appropriate engine (not replacement engine on the same boat as it is now knackered!) as the dealer shouldn't have sold it!

Start polite and keep all documentation, don't give any originals back.

[Bobalong]

All, many thanks for your comments, very helpful.

The cracks on the inside of the transom near the top of the knees are hairline, but the one on the port side near the bottom is not; the gelcoat and possibly the fibre beneath has lifted slightly, but you cannot get a fingernail in the crack. The biggest cracks are the ones on the rear of the transom where the inner and outer hull mouldings are joined; you can get a small finger nail inside them. However, these cracks do not change size when the engine is wiggled up and down.

I researched the engine weight issue a bit more; the user manual (original and new) and the CE plate on the boat state a power range of 19-25hp and a max total load, including engine, of 650kg. The engine weight limit is in the manual only and states 65kg (original manual) and 85kg (new manual). The Tohatsu 25EPT 4-stroke engine I use weighs 81kg according to the engine manual; all other comparable 4-stokes are in the range 71kg - 81kg from what I have found on the internet. This says to me that with the original weight limit of 65kg for a 25hp engine, only a 2-stroke could be installed. Even the Evinrude 25hp Etec weighs over 70kg, so for 4-strokes the new limit of 85kg makes much more sense. However, my real concern is what engine weight limit was in the design spec? The increase from 65kg to 85kg is 31%, which in loading/stress terms is a lot, particularly if the increase was arbitrary! Either way, it seems that the transom and supporting structure is not structurally up to the job, particularly given the boat's CE Design category "C".

I checked the boat logbook today and I have recorded 23 hours total use, of which only 7 hours have been on the plane, with a maximum of 2 people on board, mostly on calm or only slightly choppy water, at speeds up to 24kt. About 2 hours of the planing time was on water rough enough that, for comfort, standing at the console was preferable to sitting, and I kept the speed at about 18kt. The boats CE design category is "C", which means it is suitable for F6 winds and 2m waves, and I have not been out in conditions even close to that; if I had been, it would have been at displacement speeds! The maximum wave height I have encountered so far is about 1m, and most of the planing has been in estuaries (Southampton Water, Camel Estuary), where the waves were smaller.

Given all of the above, does anyone have any additional views or points prior to me raising the matter with the dealer? Also, if I decide to get a replacement hull, can anyone recommend a RIB in the range 3.6m - 4m or so that would get acceptable planing performance with my existing engine? Very grateful for any advice.

[kerny]

Bobalong, as I have been in the same position as yourself earlier this year I can understand your feelings on this matter, and I think the worst part of it, is the "not knowing" of how your dealer will respond to the problem. If your dealer has a good reputation I am sure that they will help you out in the best way possible.
The sooner you speak to them the better. BTW I got a full refund on mine so when you speak to him/her remain calm and polite. But be assertive

I hope your problem will be resolved soon.

Steve.

[Bigmuz7]

Originally Posted by Bobalong

I researched the engine weight issue a bit more; the user manual (original and new) and the CE plate on the boat state a power range of 19-25hp and a max total load, including engine, of 650kg. The engine weight limit is in the manual only and states 65kg (original manual) and 85kg (new manual). The Tohatsu 25EPT 4-stroke engine I use weighs 81kg according to the engine manual; all other comparable 4-stokes are in the range 71kg - 81kg from what I have found on the internet. This says to me that with the original weight limit of 65kg for a 25hp engine, only a 2-stroke could be installed. Even the Evinrude 25hp Etec weighs over 70kg, so for 4-strokes the new limit of 85kg makes much more sense. However, my real concern is what engine weight limit was in the design spec? The increase from 65kg to 85kg is 31%, which in loading/stress terms is a lot, particularly if the increase was arbitrary! Either way, it seems that the transom and supporting structure is not structurally up to the job, particularly given the boat's CE Design category "C".

As I have come to realise, the CE mark counts for didly squat, despite peoples understandings of it..

Back to a point I asked earlier .. is it possible you have a boat that was only rated for the 65 Kilo engine .. ie an older model ? Have you checked a serial number from your hull and confirmed this with the manufacturer ?

It may well be that they modified the transom at a later date to accommodate the extra weight ?

[Bobalong]

Bigmuz,

thanks for your points, and I agree! However, regarding the engine weight limit issue, the dealer originally offered me the Evinrude ETEC (71kg) until he realised he could not get electric trim and tilt with the short shaft version. Then he offered the Tohatsu. At that time I knew nothing of the engine weight limit. I only discovered the limit because I wanted to calculate the total weight of the boat and engine on the trailer for towing and winching, and I noticed that the engine weight exceeded the maximum stated in the boat manual. On raising the matter with the dealer, he said he would look into it and then came back to me saying that the 65kg limit in the manual was a typo and that it should have read 85kg. I subsequently received an updated manual. I have no knowledge of the hull design changing at all; if it has, the dealer must surely know about it and in which case I am pretty unhappy if I was sold a pre-mod boat with a post-mod engine weight limit!

However, having thought about it, my feeling is that the 19-25hp limit, with 65kg max engine weight, was for a 2-stroke. Therefore the dealer has sold me an engine that was always going to be too heavy for the boat, even though the engine power was within limits. I guess that to him, amending the engine weight in the manual seemed an easier option than me returning the boat to him and thus him losing the sale completely. I think I probably have a fairly strong case for mis-selling, and also a strong case for the boat transom being incapable of supporting the supplied engine. However, how the dealer responds to this is another matter entirely. I need to check what my rights are in this situation.

[Bobalong]

Further to the above, if the engine weight limit of 65kg was to remain, the maximum engine size for a 4-stroke would be limited to 20hp. The performance with a brand new 25hp 4-stroke has been ok; slow to get on the plane with 2 people on board but does up to 21kt, increasing to 24kt if only one person on board. With only 20hp on the back I would suspect the planing performance would be marginal at best with any passengers, assuming you could get the boat on the plane in the first place!

[Bigmuz7]

Ok.. I was just trying to determine whether or not it was an error on their part when they rigged it, or whether or not they have attempted to mislead you, because of what you said about producing a manual with different weight specs on it at a later date, since, that way it might be easier to force the dealer to replace the goods, because you could prove he sold you something inapropriately.

As it stands, due to the time scale you will be deemed to have 'accepted' the boat and you will be past the point of rejecting it as not fit for pupose IRRC, and it would now be case of you giving the dealer the option to repair it (or replace it at his option), but the repair option will be the favoured one.

In the mean time, as a back up for you, and if you can afford it, I'd have a marine surveyor take a look and give you an inspection report on the hull, assuming he concludes what we suspect here, it will strengthen your position, because you will then have an expert opinion, and is more weight to hit the dealer with ... the dealer will then have to sort it out between himself and the boat manufacturer. I say this with the knowledge that some dealers wont put up an arguement, and might be happy enough to help, but you will want to know that the repair has been a professional one and not some tatty patch up, thats where the surveyor ads weight to your position, in the end you may be able to recover the survey costs from the dealer too.

[Doug Stormforce]

I think you should find out what the deal is with the weight limit. The dealer is being painted in a pretty poor light in true ribnet fashion ( the facts are not yet known).

Find out from the builder if the weight limit was changed, and when, find out if your boat is subject to the new or old weight limit. They will be able to tell you based on hull number which design you have. Then and only then can you go back to the dealer, it may be that he has done nothing wrong and it's simply a warranty issue. It may be he has made a mistake in applying the new weight to an older hull or it may be he has lied, I suspect the first option is the most likely.

[biffer]

Find out about the weight limit. If you are over I don't think you have a leg to stand on. That's not to say you are in the crap. It's fixable