Retrofit elephant trunks?

mark_j · 12 November 2009, 09:13

I have a problem with my bung, allow me to explain. Had my first "stuff" the other day and totally swamped the rib, had to lean right over the transom and undo the bung, not ideal and very awkard.

If you undo the bung to start with, as soon as you stop for any amount of time the rib will take on water to the extent of wet feet.

Ideas on a postcard to??

biffer · 12 November 2009, 09:37

is that your only means of removing the water from your boat while at sea

andyxs · 12 November 2009, 10:44

i would say an elephants trunk is a must for any rib. a 2cm hole in the back of the boat is not enough!

mdt · 12 November 2009, 11:28

Quote:

Originally Posted by mark_j

Ideas on a postcard to??

I would suggest posting a shot of the inside of the transom as it is the internal lay out that will dictate how and where you are going to be abel to to drill a 4" hole

9D280 · 12 November 2009, 12:27

Mark,

Firstly, welcome to ribnet!

Two things - Firstly yes, a trunk will empy the boat a LOT quickwer than that wee hole. Secondly, is that bung in your photo attatched to the inside of the hull, or the cavilty under the floor? It looks a little too low to be a hull drain.......

As for the trunks, there are plenty of people will sell you a ready to fit trunk. (I got a pair of them form Humber to replace my knackered ones for (I think) about £40. No idea what your internal layout of the boat is, but leading the release string forward to the console is also a useful mod....

In the meantime, I suggest you pack a bucket. (seriously - I swamped my old SR4 "sans trunks", and was sooooo glad I had one with me!)

mark_j · 12 November 2009, 12:59

Yes that is the only drain at present, i will take pics of the inside layout but at the back of the boat is a built in bucket for want of a better word, the bottom of that is the other side of the bung. so yest you can cut a larger hole than is there at present.

Observer · 12 November 2009, 13:53

Quote:

Originally Posted by mark_j

Yes that is the only drain at present, i will take pics of the inside layout but at the back of the boat is a built in bucket for want of a better word, the bottom of that is the other side of the bung. so yest you can cut a larger hole than is there at present.

I think you're describing a "well" - a cavity at the transom that collects water and keeps the deck dry - usually equpped with an electric pump discharging though a hole in the transom. If you're likely to be stuffing the boat, you need more drainage than a well/pump can provide - so elephant's trunk(s).

Quote:

If you undo the bung to start with, as soon as you stop for any amount of time the rib will take on water to the extent of wet feet.

Yes it would. The bung on the outside of the transom (in your photo) is for draining the under-deck cavity when the boat is on land. It's not designed to drain water when you're afloat and I'm surprised it managed to get rid of any, even underway.

two stroke mick · 12 November 2009, 14:17

I installed a 68mm trunk into my Valiant which I purchased from the rib shop. I filled the original 50mm ope (which had a 25-30mm one way valve which was Sh*te). I then drilled out the 70mm hole with the drill bit centered on the filler which I placed in the original ope. The trunk is much better than the one way valve.

mark_j · 12 November 2009, 14:22

Yes a "well" is exactly what i have and the bung is quite blatently not big enough. So we have established that i do need an elephants trunk, next question is where and how to fit it?

JSP · 12 November 2009, 14:52

http://www.rib-shop.com/product.asp?...hFor=&PT_ID=23

kwil · 12 November 2009, 15:00

Mark - I notice your rib is a Porters rib as is mine. I have attached a photo of how mine was done by Porters it has the small drain in the sump for emptying when on trailer and a trunk at deck level for when under way. I also have fitted an auto bilge pump in the sump and hardly ever have to use the trunk.

Keith

mark_j · 12 November 2009, 16:05

Quote:

Originally Posted by kwil

Mark - I notice your rib is a Porters rib as is mine. I have attached a photo of how mine was done by Porters it has the small drain in the sump for emptying when on trailer and a trunk at deck level for when under way. I also have fitted an auto bilge pump in the sump and hardly ever have to use the trunk.

Keith

Keith,

Many thanks for your input. I now know what and where, I hope someone will be along soon to advise how.

Mark

JSP · 12 November 2009, 17:26

There's been a few people fitted their own on here. As far as I know (never done it myself) you need to find the best place for it to go. Drill a hole big enough and then seal that hole with something like sikaflex. Fitting the kit from RIBshop should be very straight forward.

chewy · 12 November 2009, 17:55

I sealed the hole in my transom with resin first then put sikaflex in the hole to seal it completely.

Jizm · 12 November 2009, 18:44

very important to keep the plywod transom core dry...

Downhilldai · 12 November 2009, 19:05

Some RIB manufacturers, eg Osprey, use a length of pipe (68mm downpipe, or 82mm soil pipe) through the transom, seal it in place and stick the trunk to the bit that protrudes out of the back of the transom. Others, eg Ribcraft & Avon, line the hole with GRP and use a trunk with a flange which is screwed to the outside of the transom.
Whichever way you decide to do it, cut the hole out with a good sharp core cutter. If you decide to use some pipe to line the hole, then drill the hole horizontal, rather than perpendicular to the transom face, to keep the trunks horizontal when deployed. Stick the pipe in place with plenty of Sikaflex, to prevent any water ingress.
If, on the other hand, you decide to use a trunk with a flange, then the angle of the hole cut out is less important. In this instance, I would cut some 2" wide strips of chopped strand mat and lay up 2 layers inside the hole against the plywood core, then finish it off with some flowcoat.
If you think all this may be beyond your capabilities, it may be worth having a word with Ribcraft in Yeovil, to see if they will do it for you.

mark_j · 13 November 2009, 07:53

Quote:

Originally Posted by Downhilldai

If you think all this may be beyond your capabilities, it may be worth having a word with Ribcraft in Yeovil, to see if they will do it for you.

Many thanks Dai, just of to get some hole cutters, in for a penny and all that!!!

Downhilldai · 13 November 2009, 08:30

Nice one!
Remember my old man's rule in these matters:

'Measure twice & cut once'

JSP · 13 November 2009, 08:40

Quote:

Originally Posted by Downhilldai

Some RIB manufacturers, eg Osprey, use a length of pipe (68mm downpipe, or 82mm soil pipe) through the transom, seal it in place and stick the trunk to the bit that protrudes out of the back of the transom. Others, eg Ribcraft & Avon, line the hole with GRP and use a trunk with a flange which is screwed to the outside of the transom.
Whichever way you decide to do it, cut the hole out with a good sharp core cutter. If you decide to use some pipe to line the hole, then drill the hole horizontal, rather than perpendicular to the transom face, to keep the trunks horizontal when deployed. Stick the pipe in place with plenty of Sikaflex, to prevent any water ingress.
If, on the other hand, you decide to use a trunk with a flange, then the angle of the hole cut out is less important. In this instance, I would cut some 2" wide strips of chopped strand mat and lay up 2 layers inside the hole against the plywood core, then finish it off with some flowcoat.
If you think all this may be beyond your capabilities, it may be worth having a word with Ribcraft in Yeovil, to see if they will do it for you.

I think I explained it far better than you did

ashbypower · 13 November 2009, 16:43

Also don't forget to Mask the area and to drill from both sides to prevent the gel coat "Scabbing" i.e when the centre drill "Pilot" is through let the hole saw cut slowly on one side for a few Mil's then cut through from the other side, if that all make sense

Oh and yes take is slooowly