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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jan 2020 at 9:55am
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Titanium
Titanium


Joined: 14 Oct 2013
Location: Sth Auckland
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850kg 60 hp use same 145 for hull constant
26 mph  WoT
 Do you really need the extra layers?
 Laminating the areas highly exposed to sun could end up being a mistake in the long run.

Considered using under gunnels as buoyancy chambers.
 Having them higher should aid to keeping the boat cabin up. (??) Which could also mean can foam fill.(?)
 And not loose any stowage space.

 you mention pumps/  volumetric dispensers.
We used to measure out when hand mixing, by weight on scales to +/- 2gm.
No bubbles , leaks etc.
 Keep in mind when doing so the volumetric weight , ratio required will be a little different to the weight ratio due to the specific weight of each component
A mistake many painters etc have commonanly made.
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jan 2020 at 6:29pm
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Platinum
Platinum


Joined: 19 Jan 2013
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I rang adhesive technologies today re WEST ratios. 5:1 is fine by either volume or weight. Ideally by weight though 5.2 or 5.4 to 1 is better if I can manage that. There is more leeway being a bit resin rich than hardener rich.

I used scale for todays job: splicing panels. Had to chuck a batch when I needed to change epoxy bottles halfway through the pour, when I had the pump screwed in the new jug, I added the amount I thought it would be by memory, but didn't trust it. It cured in the pot ok.


Edit: My scale will auto off after a minute or so. Usually not an issue.
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jan 2020 at 8:04pm
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Platinum
Platinum


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Glass on sole and sides, is purely for impacts  while docking etc. Not required as such, but listed as an option, extra glass on bottom panels recommended if one is expecting to use more power than suggested, or if one is expecting hard and heavy usage. I think roller trailers on NZ roads may qualify Tongue

At this stage the cost in weight isn't particularly much, and the extra glass is a non issue. I bought a 50kg roll (more economical) so have more than twice the amount I need. I also have learned that adding glass will never be easier than now. 

At the end of the day it's my boat and I'll sleep better with a bit more glass than the minimum listed on the plans. No matter what I do it will still come out lighter than an equivalent glass or aluminium boat. 
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jan 2020 at 8:26am
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Titanium
Titanium


Joined: 14 Oct 2013
Location: Sth Auckland
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I think roller trailers on NZ roads may qualify Tongue

 You mean non keel wobblies?

Thats maybe a though thinking right thru..At this stage rather than later.

Old school keel boats where designed to take the weight on a keel roller trailer with side rollers there to keep even.. Correctly setup the side rollers should be able to just be turned by hand when boat not tied down.
 Wobblies on a non keel trailer , not positioned well on a keel boat can cause problems breaking the glass corrugations formed over the stringers,
Stress on hulls between between bulk heads etc

Modern non keel boats construction tends to be a bit different in placing of bulk heads and such match trailers or visa versa

I had a minor incidence a while back.. new truck, hitch different height , loading on hitch too light. Moved the boat forward about 3/4" did not re set the side wobblies.. punched a very minor crack in the hull about 1" inside the chine, going over a speed hump.
 We leaked around 2 to 3L over a 8hr day.
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan 2020 at 12:12am
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Platinum
Platinum


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I've given it a fair bit of thought. 

The designer assures me that:
  •  Rollers will work though bunks provide better support. 
  • The bottom panels should be stronger and stiffer than the equivalent 8mm glass layup . (This depends on my workmanship, but he had panels tested by a engineering dept in a uni, by both expert and novice laminators.)
  • Rollers or bunks they should be under the stringers. 
  • Typical wobble roller arm width in NZ is 300mm, 400mm or 500mm. 
  • Along the back 2m of the boat where most of the stress is the stringer to chine distance is 400mm. Stringer to keel is similar.
I'm planning to either build a trailer to suit the structure of the boat, or if I get a trailer first, I'll put internal structure where the rollers are. At this stage of the build it's not a big deal to ensure that the stringer layers or chine laminations extend to where the rollers go. That would be 2 layers of 400g on one side and 3 layers total on the inside right on top of the rollers. At this stage I am leaning towards a 300mm wobble roller with one under the stringer and the other 100mm inside the chine, where I will have reinforcement. 

Keep in mind that your boat would have much more load on the trailer than mine. 6m glass vs 5.3m wood epoxy composite. 





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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan 2020 at 12:15am
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Platinum
Platinum


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I went hiking today but spent a few hours at the end of the day splicing the other side of my bottom panels. I think I've done this side much better than yesterdays, where I will have some voids to drill and fill. They really only need to be strong enough to hold together while planking, but I don't want voids anywhere in this hull if I can help it. 


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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan 2020 at 12:17am
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Platinum
Platinum


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 Voids visible, side underneath has glass on it. I should have butted the panels into some putty.




Cleaned up and ready for putty and glass. At least glass on the other side acts as a scrim for the putty, and I can fill it later. 

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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan 2020 at 10:25am
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Titanium
Titanium


Joined: 14 Oct 2013
Location: Sth Auckland
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Points: 9279
Keep in mind that your boat would have much more load on the trailer than mine. 6m glass vs 5.3m wood epoxy composite.

No 5.5m glass, not 6m

I would not, regardless of what anyone says, rely on an extra layer of glass, or even more layers within reason to provide enough strength in a hull, between bulkheads .. even thu a stringer or chine very close.
 You are putting a sudden thump from a pot hole or a speed bump, onto a VERY SMALL area that has a huge impact properly going into several tons / per inch... and even more so if it is a keel boat on wobbles.

Keep in mind a bottom hull impact strength is designed to take a hit on the same plane the boat is traveling in.. a glancing hit....a supporting wobbly is direct 90 deg impact.
 If want to strengthen for that, use plate steel.
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan 2020 at 2:35pm
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Platinum
Platinum


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Several tons per inch? Given that the average roller should support about 25-40kgs that’s well over 10g acceleration. If that were the case in normal use no boat would survive a wobble roller.

I’ll keep what you say in mind but at the end of the day it’s my call. I might give figlass or someone a ring. Anyway out to glue the transom.

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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jan 2020 at 9:18am
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Titanium
Titanium


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Several tons per inch? Given that the average roller should support about 25-40kgs that’s well over 10g acceleration. If that were the case in normal use no boat would survive a wobble roller.

 lets use the old example, a ladies stiletto shoe heel..
 She may weigh say 70kgs, but the pressure on that small area of the heel.. from memory.. works out to around 10 ton ..maybe was 1 ton.. whatever thats a a huge amount of pressure.
 Now apply that to th every small area of hull, that is in contact with the top edge of a wobbly....

I put a small crack in my hull.. next to a chine cause hull was sitting just a little heavy on a wobbly.. not supported fully by the keel... in between bulk heads... and hit a speed bump... and even slowed down for it.
 And its not an uncommon repair.
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jan 2020 at 9:31am
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Platinum
Platinum


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Weight of boat on trailer ~700kg. Divided by 20 rollers =35kg per roller.

Surface area on a roller 7.5 square cm.  (rubber roller with the little flats.) 

That's about 5kg/cm2.

Multiplied by unknown factors for impact, and a safety factor of 5 (for long fatigue life.)


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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jan 2020 at 9:54am
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Titanium
Titanium


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20 rollers.. now that makes sense...
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Post Options Post Options   Likes (1) Likes(1)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 02 Feb 2020 at 6:39pm
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Platinum
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I haven't posted in a while, but have been busy. I had issues with some voids in my stringer and transom lamination, especially the stringers. The cause was basically uneven pressure and possibly not enough glue. 

Anyway, I bit the bullet, decided that the stringers would need to be redone (again!) and scrapped the transom as well. Cost for two more sheets of 9mm marine ply =$200. I'm hoping to salvage some of the scrap for the cradle when I flip it or cleats or something so it's not a total loss.

This time I did what I should have done for the start. I used screws and plenty of them. Precoated both sides, spread the epoxy (thickened to at least mayo) and then used hand tightened screws in predrilled pilot holes. Worked a charm. 

Photos of new transom ready for last layer of 9mm ply.
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb 2020 at 9:03am
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Titanium
Titanium


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Anyway, I bit the bullet, decided that the stringers would need to be redone (again!) and scrapped the transom as well.

Full credit  plus more for that attitude..there are many projects, not just boats where ppl keep on keeping on .. then find at the end , nothing fits and strength etc is compromised.

A extra mm here another there , espec in early stages, will end up having you tear your hair out later cause stuff doesnt fit...


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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb 2020 at 11:47pm
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Platinum
Platinum


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Yeah. I'm not too fussed about gaps in joinery or whatever but voids in a structural lamination? Not if I can help it. I'll accept pin holes here or there I suppose. I know some production boats come of the line with much worse if some of the pictures out there on the net are anything to go by. 

On the brightside, I'm a lot better at ripping straight cuts with a circular saw. Used a sheet of ply as a guide, and done. Easy as. 





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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 04 Feb 2020 at 12:26am
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Platinum
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Couple of other things in my new transom:

Clamping boards go right across, 4 layers of 9mm ply total. Will get glass both sides, one layer everywhere, plus overlaps and tape in stress areas and panel joins. 

I moved the rear scuppers. These will be just above the DWL over a sump for the bilge pump. Idea is that the pump deals with the normal stuff and the scuppers are emergency use only. They will get layflat hose or  or something similar. Still thinking that through.  

I predrilled and filled with epoxy plugs holes for the outboard. The plugs are 30mm diameter, vs the 12mm bolt size. Plenty of wiggle room. Also filled the holes that will drain the motorwell. They will also be redrilled at a smaller diameter into the epoxy: No possible path for water to get to the wood. 

There was an annoying 5mm inwards bend in the transom after the first lamination. After a bit of pondering I cut a couple of kerfs, filled with epoxy putty, and screwed the transom flat to the old transom. No more bend. Then the last layer of 9mm on the top with glass to follow. The epoxy filled kerf should be stronger than the wood, and it's in the neutral axis of a sandwich, no strength issues. 












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Post Options Post Options   Likes (1) Likes(1)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 14 Feb 2020 at 10:44am
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Platinum
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After a bit of mucking around with stringers and transom I am starting to set up the jig. 

This method does not require the accuracy of a traditional jig, which is just as well. CNC cutting would be the only option for me if that were the case. 

To complicate things the ground is not perfectly flat. I checked with a hose pushed into duty as a water level. One end of the jig is 100mm higher than the other. That's about 1.5 degrees off horizontal. 

The strongback is as level as I can get it on the ground like it is, and I will make first measurements off that, and then adjust the frames so they are lined up. Hoping for +-3mm everywhere if I can get it. 

Photo of the first attempt. I quickly decided that was too high and lowered the frames 20cm so I can reach the keel. Room to get around it will be tight. 






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Post Options Post Options   Likes (0) Likes(0)   Quote MacSkipper Quote  Post ReplyReply Direct Link To This Post Posted: 15 Feb 2020 at 5:43am
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Titanium
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Originally posted by OneWayTraffic OneWayTraffic wrote:

After a bit of mucking around with stringers and transom I am starting to set up the jig. 

This method does not require the accuracy of a traditional jig, which is just as well. CNC cutting would be the only option for me if that were the case. 

To complicate things the ground is not perfectly flat. I checked with a hose pushed into duty as a water level. One end of the jig is 100mm higher than the other. That's about 1.5 degrees off horizontal. 

The strongback is as level as I can get it on the ground like it is, and I will make first measurements off that, and then adjust the frames so they are lined up. Hoping for +-3mm everywhere if I can get it. 

Photo of the first attempt. I quickly decided that was too high and lowered the frames 20cm so I can reach the keel. Room to get around it will be tight. 






great winter project enjoying following it....
Good fishing trip nothing breaks, great trip catch fish.
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 16 Feb 2020 at 11:27am
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Platinum
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Well the stringers and transom are basically done, I am calling them done. Glassed over the transom top with two layers biaxial tape offset a little bit. Had to cut out a few voids in the first layer where it lifted. Filled with epoxy PB.  Second is curing now. 

The jig is nearly complete, Frames A-E all lined up as accurately as I can, with a lot of measuring of diagonals. The ground is on a slight slope, so I am squaring off the strongback then checking measurements and adjusting so the notches lie even with the stringer (useful straightedge). 

 I used the trick of drilling a 10mm hole in the frames at BL and CL and pushing a bike LED light into frame E. The light is visible through a hole clamped over the CL of frame A (Frame A doesn't go through the baseline.)

Next step is to notch the stringers so they fit flush in the frames, then fit the motorwell frames and hang the transom. I'll probably support it from below and screw through the putty filled holes for the outboard bolts.
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 16 Feb 2020 at 11:30am
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