SIB: Alu floor damage - any tips?

Glaerox · 12 June 2019, 10:43

Hello All.

I own a Mercury 365XS Adventure. This is the third season that I use the boat. despite some flaws I really love this boat. It performs well and it looks great!

But now I have a problem I don't know what to do with:

The situation: 365XS adventure with Mercury 20HP 4-stroke. Only assembled once a year (stored on trailer).
I live near a river called the Ijssel. Some freight ships use the river and they make big waves. I always have fun riding those waves. Never had a problem before. This time we were with 3 adults. Catched a wave but the boat hits the second wave with the Bow first. The bow bends back\up. Never seen it before but had the idea it would do any harm.

This weekend I noticed that the third (alu) floorboard is bended where a channel is that catch the other (second) board. So the wave did do some damage to the boat. I thought those boats could handle waves pretty well, it has a C rating. See the drawing below for the current situation.

What to do? Can it do any harm? Will it eventually break as alu breaks easy when bended\stressed. I am not sure if the lower side of the panel is bended to (where the ? is). I cant feel it and don’t want to disassembling the boat mid-season.

I can buy a new panel (£250) but with the next big wave it happens again.
I can press the top of the channel back in shape (already hammered it back a little to prevent dirt getting in the gap), but maybe it breaks with the next big wave when its stressed again. Maybe welt a little stroke of alu as reinforcement on top of the channel. But maybe something else will break when hitting a big Wave…
Or leave it as it is and put a little kit in the gap every season. As the second floorboard is a little further in the channel of the third one the floor is a little shorter to (5mm)
Any other options?

(Attachments)
1. picture for overview)
2. Picture from channel. At the red line the floor is bed up (hard to see on picture).
3. Paint drawing of floor (side view).

Thanks for reading!

jeffstevens763@g · 12 June 2019, 11:02

hi Gaerox

i have the hd 365hd because the front two boards rotate at that joint normally i wouldn't bother too much my guess is that you were down on pressure in the tubes and keel allowing it to bend it sounds like you hit a standing wake wave off the ship much like hitting a brick wall. it might be a weak board too so £250 might be the way to go. inside the boards there are uprights to strengthen the board so i dont think it will bend much more but i wouldn't try to straighten it will make it weaker.

pagick · 13 June 2019, 18:04

A few weeks ago I read on this forum about using electrical tape on these joints to stop squeaking. Perhaps a few layers of tape will spread the two boards apart and only the now open edge is an issue. And I am guessing it's not an issue. As mentioned aluminum only likes to bend once. So try it without re-bending it. But if needed you can try to grind or saw off the extra length of the two.
I'd guess you can use it like it is just so the bent bit isn't touching the main tube or floor.
P.S. I also agree your boat was probably under inflated.

Locozodiac · 13 June 2019, 19:01

You need to inflate the boat to at least 3.0 PSI once floating on water after overall pressure has stabilized from where originally was inflated to. If wanting a firm boat get yourself a presure gauge. That's a large SIb, needs to be fully inflated to achieve best rigidity and water performance.

Check if possible to buy just the bent rail and not the costy whole alum floor section. Tapping the floor edge is only good to cancel squeaky noises when boat is under way....

Happy Boating

Glaerox · 14 June 2019, 10:59

Thanks all for the response and tips!

It happened on the first day I used the boat this season. It was assembled about an hour before use. I always use the pressure gauge that came with it. I also have a pressure gauge of a smaller Suzumar that I own (like the one on the picture of Locozodiac). I will try that one and compare it with the quicksilver one (that looks a lot “cheaper”). I inflate according instructions in the manual: 3.6 PSI (0.25 bar) for the tubes and 6.5 (0.45 bar) for the keel.

I will not try to straighten the bend channel of the floor and just try this season how it will perform. I can always order a new floarboard in the winter or ask around if they know the manufacturer of the floorboards and maybe get only a small section to get this one repaired.
Safety first. If I don’t trust it I will order one straight away!

jeffstevens763@g · 14 June 2019, 12:46

Quote:

Originally Posted by Glaerox

Thanks all for the response and tips!

It happened on the first day I used the boat this season. It was assembled about an hour before use. I always use the pressure gauge that came with it. I also have a pressure gauge of a smaller Suzumar that I own (like the one on the picture of Locozodiac). I will try that one and compare it with the quicksilver one (that looks a lot “cheaper”). I inflate according instructions in the manual: 3.6 PSI (0.25 bar) for the tubes and 6.5 (0.45 bar) for the keel.

I will not try to straighten the bend channel of the floor and just try this season how it will perform. I can always order a new floarboard in the winter or ask around if they know the manufacturer of the floorboards and maybe get only a small section to get this one repaired.
Safety first. If I don’t trust it I will order one straight away!

exactly the same pressures as mine so no probs there i guess you have just been unlucky and hit the wave wrong & too hard ive been out in some really rough conditions in mine it never fails me and takes as much stick as some RIBS do. but your right if you dont feel confidant get it swapped out price of injury and all that.

Locozodiac · 14 June 2019, 19:22

Have had 7 different size Sibs before passing to a Rib, all were same type as yours. What find really strange is why factory recommends to fully inflate the keel to an astonishing 6.5 PSI when all other same type Sibs from other manufacturers recommends to inflate to max 3.5-4.0 PSI. Used to inflate mines to 3.5 and worked perfect.

One issue that's not been taken into account by the factory is that if inflating the keel to such working pressure will exert more up pressure under both bow wooden panels and consequently add more pressure and stress to the 2 alum male and female rails where they join together.

In Sibs that has one large bow wooden panel, such keel pressures will end warping the middle section in the long run specialy during constant summer uses.

Max 4.0 PSI keel inflation will suffice, will provide a good lower hull water performance with much less stress on wooden panel's matching rails. Test, nothing to lose, much to gain..

BTW, at 250 pounds for a complete panel is an out of this world price, we sell those for US $ 100. The air valve adapter seen on picture was machined to fit nicely those Halkey Roberts air valves tight along adding a nice big dial Scorprega Presuure Gauge.

Happy Boating

Locozodiac · 14 June 2019, 19:26

Ooops double post sorry, please remove...

jeffstevens763@g · 14 June 2019, 20:21

The keel inflation pressure is greater because the fabric is an heavey duty material the pressure is needed to stretch the hull fabric tort for a more streamlined hull. Don't forget that the tubes and keel arnt solid distorting slightly allowing for bend, twist and squash the bow lifts and lowers to allow climb up the wave face and the boards are ply in the bow which are more suited to the application. Recommended pressures allow for rise and lowering temperatures without massive effect to boat performance 1 degree rise or lower in Celsius is = to 0.045 bar pressure increase or decrease.

Glaerox · 17 June 2019, 10:43

Thanks again for the replies!

I launched the boat last Friday and compared both gauges. I think the "cheap" quicksilver gauge is not accurate. When the Suzumar says 0.25 Bar the Quicksilver one shows 0.22 Bar. It is possible that the boat was by 10% to low on pressure when we hit “the wave”. Can 10% really make the difference?

The boat performed well (The water was smooth so no real test). I think I will continue to use it this season and take the floorboard next winter to a metalworker. I hope he can replace a small part of it. When not I order a new floorboard just to be sure.

also I will start saving money for a small (4.5M Rib) ��
Thanks!

Locozodiac · 19 June 2019, 19:38

Quote:

Originally Posted by jeffstevens763@g

The keel inflation pressure is greater because the fabric is an heavey duty material the pressure is needed to stretch the hull fabric tort for a more streamlined hull.

Really, forgot to mention that all my previous owned Sibs were built with 1.2 mm German fabics and all performed spot on, provided the factory glued the lower fabric well to be displayed stretched firm once fully inflated to those mentionded way less pressures.

Pics are much better than 1K written words, corresponds to heavy duty 380-420 Sibs working with keels inflated to 4.0 PSI used for towing surfers on daily basis. Those Sibs must pass a continous 10 row wave area to reach the safe towing are. So far with 0 bending issues as seen on the OP's alum rails.....

Happy Boating

Glaerox · 20 June 2019, 07:02

Thanks once again for the extra input.

Next time i use the boat I will make sure to inflate it to the recommended pressure. I am planning to use it tomorrow with 3 friends. I will catch some waves and make some movies how it performes.

Fenlander · 20 June 2019, 10:26

Glaerox looking at your images again I wonder if the red nose of board two should butt into the curve of board three before there is any contact between the flanges of the boards. Even with a properly inflated alloy floor SIB there will be a degree of movement and if the is space between board nose and matching curve it will always be the tendency of those too to try and meet.

Might the answer be to machine back the flanges a few mm so the stronger interface can butt together nicely and this would stop the two flange faces riding over each other.

jeffstevens763@g · 20 June 2019, 19:59

FWIW my theory of under inflation and a hard hit into the wave allowed the bow to lift more or Buckle basically prizing the channel apart. All boards are under the tube so cannot lift independently, having the same boat ish I've never expearenced the bow movement pumping mine up to the manufacturers pressures

Locozodiac · 23 June 2019, 19:55

Is that Sib the pointy nose model ? If so, use to sell those, but personally didn't liked having 2 alum panels at bow. Now all Sibs have D bows ones, one piece large wooden panel. Under both bow alum panels and hull rests the rounded keel portion which flattens out on its way towards the transom.

When keel is over inflated, this portion exerts too much up pressure against the edge of the first bow alum panel when a wave hits under the hull's formed tent. OK for general boating not for jumping waves continuously, if want to keep doing so, expect a high repair cost...

BTW, can't modify the front panel's edge length nor the U groove depth of the side panel as it's a fixed. Check if possible to replace just the complete front slat as in picture.

Happy Boating