Replacing my speedboat floor

[Rodg98133]

As some of you are aware I am in the process of replacing the floor on my 18' Broom Aquarius speedboat. I have taken all the old floorboards out and wired up a bilge pump as there wasnt one in there before but have a few questions on where to go from here

1. At the back of the boat I have taken the floorboards up to about a foot from the rear where there is a bulkhead under the floor. The problem is that there is no drain hole in this bulkhead so any water that gets it the front of the boat cannot be drained via the bungs. Can i make a drain hole in this bulkhead so that the water goes all the way to the back of the boat?

2. There was no foam under my floorboards. Everything ive read online about replacing the floor says that there is foam under the boards for boyancy. Does it need any or will it be ok as there doesnt appear to have been any so far.

3. When laying the new floorboard I am going to cut them to shape but then wanted to seal them before laying them. Will polyester resin be ok to seal the boards just painted on and then once they are layed im going to glass over them to try and seal it as much as possible.

I think thats all for now.

 

[rob2]

I don't know anything about the construction of the Broom, so can't answer the first two questions!

On the third, though I'd be careful to choose a thickness of ply which won't flex noticeably, probably 18mm although this will be heavy (WBP or marine). Polyester resin is not brilliant for sheathing, many older boats had decks sheathed in it and after a couple of decades it flakes off. Epoxy resin is very good, though and should be painted all over the boards, then a thin tissue used to sheath it to add skin strength. Unfortunately, that's the expensive part and epoxy breaks down in UV so it's normal to varnish over with a UV filtering varnish for looks or any old paint for wear. Masonry paint is often used to give a tough finish under foot with non-slip properties - particularly if you are going to fit carpets but lift them when under way.

Rob.

 

[antaris]

Generaly speaking, it is not unheard of to drill holes in bulkheads - just make sure that you properly seal the holes with epoxy (or similar), so that you don't get your bukheads rotting away (I presume there's plywood in there).

Adding the foam as described might also be a good idea, positive floatation is a welcome bonus in small boats.

 

[Rodg98133]

Polyester will flake off after a decade? Thats fine by me, ill probably get bored and buy something bigger within the year lol.

With regards to adding foam what would i use? Just like the insulation foam boards chopped up to fit?

 

[antaris]

I believe that you should use closed-cell foam (that does not hold water/humidity inside).

Adding foam will greatly affect the amount of work that needs doing (+expense). You'd need to epoxy the foam to the hull (so that it does not float away if boat gets flooded!), seal it all around and then add the floor (you could also glue that to the foam, although I'd leave it for inspection purposes). On the plus side, you would not need a bilge pump - not under the floorboards, at least!

{please keep in mind that I am NO professional, take my advice as friendly chat and not professional advice!}

 

[Uricanejack]

Just my opinion but some the advice so far is *******s from folks unfammiliar with the type of boat. be care full you don't add to much weight the boat was originaly designed to be light and plane.

I have had small old runabout 16ft grp with, ply deck, bulk head and transom.
The decks will eventualy get wet and rot this can happen to bulk heads and transhom as well.

I patched localy first didnt work for long.
Get you saw out an cut out whole deck.
under deck you will most likly find longitudinals going entire lenth often soft wood. its lighter.
Chech longitudinals for rot. I was lucky my deck had remaied intact long enogh I did not have to replace longitudinals. my bulkheads and transohm were ok.
If they are wet and soft they will need replaced. you could dry and cut out any soft spots but you will need to put doubler along beside a thin 1/8 in ply would do. but better to replace. cut out use as template for replace ment of same sise wood. I would have cut new longitudinals out of 1/2 in ply
then glass in place.
When removing old you want to do as little damage as possible to use as template for replace ments. getting all the right depth and the deck level will be a bugger other wise.
I used a large sheet of card board and an exacto knife and a steel rule to make template for new deck.
I used 1/4 ply for deck a bit more than original. the strenth is in the suport from resting on top of longitudinals.
original construction had steel screws to screw down deck. I used glue and brass screws.
I used regular grade ply due to cost of marine grade and dificulty finding then painted with resine. taped along all seams then put layed of glass and resinge over all..
By making the deck watertight as was original designe the reserve bouyancy is stll there. i thought about putting foam in but concluded being carfull to ensure was watertight was better.
increasing thickness of deck ply will increas weight to much and you will adversly affect performance.
a buddy redid his using extruded aluminum for new deck. lovely job but he has a 150hp to power his 18ft. I have a 55 on my 16ft.
I spend a hell of a lot less on fuel.

 

[antaris]

uncecessary foul language there, we're only here to exchange ideas and chat

 

[Boathook]

Just my opinion but some the advice so far is *******s from folks unfammiliar with the type of boat. be care full you don't add to much weight the boat was originaly designed to be light and plane.

.

I do feel that your comment about some of the advice is wrong. Personally I would replace the floor with same thickness material and trying to make it water tight could be a nightmare.

 

[Davegriff]

We replaced the sole in our 14 foot speedboat a couple of years ago. Used 9mm (3/8") ply glassed all around edges, then poured 2-part polyurethene foam through a series of 25mm holes, about 500mm apart. You need to work out the amount needed (get manufacturers notes and read up about it first) and let the surplus foam expand through surounding holes - important. Sand off flat and apply a layer of glass all over to seal sole and holes. The foam gives plenty of stiffness/support for a small craft like this.

 

[Uricanejack]

I do feel that your comment about some of the advice is wrong. Personally I would replace the floor with same thickness material and trying to make it water tight could be a nightmare.

Ill stand by my sugestion some of the advice is not good by changing the designe and adding to much weight to what is intended to be a light boat the same grade of ply is the way to go. I did find getting the deck watertight was not easy. it was the use of tape which worked. my first ttempt at a patch ussing just resigne and stips of glass leaked. when I redid replacing whole deck. I used tapeand classed over.it worked. adding foam may or may not be good. if you do be certain it wont soak up water.

 

[Lakesailor]

uncecessary foul language there, we're only here to exchange ideas and chat

You don't know the forums very well.


OP: Forget foam. Do the maths and see how much you would need to provide neutral bouyancy.
Neither grp nor the motor have any natural buoyancy.
You wouldn't be able to get into your boat for foam.

 

[oldsaltoz]

G'day Rodg,

1. At the back of the boat I have taken the floorboards up to about a foot from the rear where there is a bulkhead under the floor. The problem is that there is no drain hole in this bulkhead so any water that gets it the front of the boat cannot be drained via the bungs. Can i make a drain hole in this bulkhead so that the water goes all the way to the back of the boat?

Two options:
1. Make a hole.
2. Make a hole, and do not replace the last section of deck full width and leave a well, this will give you access to the new bilge pump and provide more deck drainage.

2. There was no foam under my floorboards. Everything ive read online about replacing the floor says that there is foam under the boards for boyancy. Does it need any or will it be ok as there doesnt appear to have been any so far.

The most effective replacement I have used is to fill the void the void with kids pool sticks, about 3 inches round and 4 feet long, closed cell foam and cheap.

3. When laying the new floorboard I am going to cut them to shape but then wanted to seal them before laying them. Will polyester resin be ok to seal the boards just painted on and then once they are layed im going to glass over them to try and seal it as much as possible.

If you are not planning on keeping her for another 10 years, you can glass the area with standard resin, but, sand it with a 40 grit in line with the grain first then a few strokes across the grain to give it a good key, do this on both sides, and do it before you install the floor.

Also note any screws through the deck should be drilled out oversized first and then filled with an epoxy (Araldite will do) then re drilled to the required size for the new stainless steel (316) screws.

I think thats all for now.

Good luck and fair winds.

 

[Rodg98133]

For coating the floorboards with the resin do i mix it with the hardener aswel or just paint the resin on?

 

[oldsaltoz]

For coating the floorboards with the resin do i mix it with the hardener aswel or just paint the resin on?

Yes, never apply resin without hardener mixed in first.

Good luck and fair winds.