fitting second seat to sr4 advice please

beerbelly · 31 August 2015, 08:55

took a pal out fishing yesterday had a great day caught loads of fish. but he complained the bucket he was sitting on was uncomfortable while we were speeding out to sea

. my sr4 has the standard dual seat that isn,t quite dual enough for 2 overweight friends (were not that friendly). so I'm thinking of fitting a single jockey seat behind . what I need to know is the best way of securing it to the deck I'm aware there are air chambers beneath the rear deck but unsure where or how much fiberglass is above them .I don't want to drill into one . has anyone added extra seating and how did you go about securing to the deck .thanks

Nick Hearne · 31 August 2015, 09:55

I would put these in to the deck, sealed in with sika then you can take them out when not needed!

beerbelly · 31 August 2015, 10:06

Quote:

Originally Posted by Nick Hearne

I would put these in to the deck, sealed in with sika then you can take them out when not needed!

do you mean just sikaflex the seat pod to the deck

Nick Hearne · 31 August 2015, 10:39

Quote:

Originally Posted by beerbelly

do you mean just sikaflex the seat pod to the deck

No, drill holes to bolt seat down, sika in hole insert nut clean off exess job done.
You can then remove the seat by Unbolting when not needed
May have to seal off the bottom of the nut as they are open or be carful when putting them in not to get sika coming back up through the middle and blocking off the thread!
This is how my original Sr4 seat is fixed in to the deck so 4 bolts and its out

beerbelly · 31 August 2015, 11:18

thanks but what happens if I drill the deck and it goes through into an air chamber. will this not affect how the flooding hull works ie I would think if I did the hull would just keep filling until water came out through my bolt holes . or am I misunderstanding how the system works

Nick Hearne · 31 August 2015, 13:27

Just don't drill deeper than the thickness of the ply!
Or screw it down again screws no longer than the deck thickness and Sika too but you wont want to be getting it out in a hurry!

Have a look here post 17 shows whats under the deck

http://www.rib.net/forum/f16/searide...t-41799-2.html

beerbelly · 31 August 2015, 13:42

thanks for the help I don't think it will be coming back out hopefully will be a permanent feature . any idea what the deck thickness may be ie what length self tappers to use

Nick Hearne · 31 August 2015, 14:18

I have read it is 10mm ply but can not confirm, but if you use plenty of shorter screws and sika if should be fine or glass it in!

ShinyShoe · 31 August 2015, 16:14

There are three methods to attach seats:

- bolts
- fibreglass
- sikka and screws

Each has its merits. Bolts let's you remove the seat if you want the space back.

Glass is pretty much indestructible.

Sikka and screws. Generally the view is the screws are just to hold while the sikka cures. Close to indestructible.

I don't know what the floor on an SR is but ply is usually in multiple of 3mm, so 10mm sounds unusual. Not sure I'd trust sikka on such a small surface area, especially a smooth polished one. So I would be looking to glass over them too, and or epoxy them in. Fill the thread with plasticine to stop adhesive getting in then pick out with cocktail stick.

How are your other seats secured...

Nick Hearne · 31 August 2015, 16:31

Quote:

Originally Posted by ShinyShoe

I don't know what the floor on an SR is but ply is usually in multiple of 3mm, so 10mm sounds unusual. Not sure I'd trust sikka on such a small surface area, especially a smooth polished one. So I would be looking to glass over them too, and or epoxy them in. Fill the thread with plasticine to stop adhesive getting in then pick out with cocktail stick.

How are your other seats secured...

I would have said it was 12mm I only came up with 10mm as it has been stated on here B4, I had not heard of 10mm B4 too!

beerbelly · 31 August 2015, 20:42

thanks the front seat is bolted down but the air chambers are at the transom end which is my only worry as I don't want to puncture one or both of them .the floor is a stippled type effect I think I could mark out the outline of the new seat and grind the surface of with a p35 disk around the outside do the same on the seat flange then sikaflex the seat inside the ground out area then glass over the outer flange to floor join. would this work and can I use glass matt and resin

ShinyShoe · 31 August 2015, 21:16

In short yes.

You will want to read:
https://www.gov.uk/maib-reports/fail...on-of-3-people
and https://assets.digital.cabinet-offic...14f/SB2-07.pdf

Glass Matt & Resin. Multiple layers. Followed by Flowcoat over the top. Personally, rather than sikka, I'd have ground off the flow on the base where its to be attached, then put a fresh layer of matt and resin and then pressed the console ontop - perhaps with some short self taps just to hold it.

Smesh · 28 October 2015, 04:25

Don't mean to hi jack or resurrect an old thread here, but can anyone explain this air chamber spoken of in the SR4?? I just bought an SR4 and there are old screw holes in the rear from fuel tank hold downs. I splashed the boat for the first time after removing the screws, and they are definitely all the way through the deck as water was leaking in pretty fast. I promptly had the hoist operator take the boat back out, and today I put the screws back into the holes with 4200. But now I'm worried about this mysterious air chamber in the stern??

beerbelly · 28 October 2015, 08:19

as far as I am aware there is 2 buoyancy tanks under the floor at the transom end to help with the weight of the outboard when the hull is stationary and flooded .I don't think that the water from the flooded hull ballast system can get into the tanks (maybe it can get around them ?) I was concerned I would lose the buoyant effect from them if I punctured them. I may be totally wrong of course

Smesh · 28 October 2015, 17:49

Quote:

Originally Posted by beerbelly

as far as I am aware there is 2 buoyancy tanks under the floor at the transom end to help with the weight of the outboard when the hull is stationary and flooded .I don't think that the water from the flooded hull ballast system can get into the tanks (maybe it can get around them ?) I was concerned I would lose the buoyant effect from them if I punctured them. I may be totally wrong of course

I saw the picture in the referenced build thread, and yes it appears there are two buoyancy chambers, but I don't know if the deck is laminated to it, or if it's just suspended on top and the water can flow over it. If it gets between the deck and the top of the air chamber, then I could end up filling it with water, since I'm pretty sure the 3/4" screws I put through the deck would have made it through to the air chamber. I guess it depends how thick the deck material is. I doubt it's 3/4" though. When I put in the stainless screws, I used the same as the ones the guy before me used at the transom, and these just went through into the flooded hull so no worries. I had no idea there were air chambers further forward, so thought nothing of it. Tomorrow I'm going to shine a light in there. I put the 3" pad eye right down the middle of the pebbled area that a fuel tank would go, so I probably pierced both air chambers, one on each side. Like a #dumbass.