Notes on a Morbic Build in New Zealand.
Posted by Nigel McC on
URL: https://forum.mymorbic.uk/Notes-on-a-Morbic-Build-in-New-Zealand-tp414.html
I began building the Morbic in mid-July. I decided to complete the spars, centreboard, rudder and stock, before starting work on the hull. In my previous builds, mostly Oughtred designs, I have completed the hull, then discovered I have another month or so of work before I can go sailing.
So I made bird’s mouth spars from imported Douglas Fir. The timber was disappointing, developing splits and gaps within the glue up. Use the Duckworks calculator to caculate the dimensions of the spar strips.
It took about 30 hours to complete the boom, yard and mast. Out of interest, I glued the boom and yard using polyurethene glue, and the mast with epoxy. I wouldn’t use polyurethene again … messy, not much quicker than epoxy, and goes off quickly
I assembled the mast in two halves, so that I could add plugs and shape the slot for the halyard sheave. The plugs seal the middle of the mast, adding floatation.
In mid September, a friend who has a second-hand CNC cutter, cut the planks and girder from Vivier’s files.
These are excellent. The girder and planks fit together in most cases within + 2 mm and the time saving is huge. Strongly recommended.
The rudder and centreboard case took about 20 hours.
I use Titebond III to glue flat surfaces, such as doublers for centreboard and transom. It’s quick and easy to clean up. There is an old study from the US Forest Service that reports Polyamide glues are equally water resistant to epoxy. However, amide glues have poor gap filling properties so can only be used for well matched surfaces.
I laminated the false stem from Ash, two to three 3 mm layers at a time, and glued with Titebond III much easier than with epoxy.
I assembled the girder and molds at the beginning of October. Again, the Vivier CNC files are fantastic. The transom, longitudinal bulkheads went together in half an hour. I finished planking by 25 October. The only difficulty was, as usual, bending the the garboards into place, and cutting the gains to the stem. I’ve glued the planks with West System 105 + slow hardener.
Time spent to date, about 120 hours, including a round trip to Auckland to collect timber.
Notes:
1. Don’t use Polyurethene glue. Use Titebond III for well jointed surfaces, and epoxy when gap filling or filleting.
2. I lined the inside of the rudder stock with fibreglass to resist abrasion; that decreased the gap between the cheeks and the rudder cap no longer fitted. I’ve had to cut the cap in two and add a further layer of 2 mm ply to accommodate the rudder.
3. I cut additional clamping holes in the centre stem-leaf because I don’t have enough long clamps to laminate the false stem
4. Cut the holes for inspection ports in the longitudinal bulkheads in advance … it will be difficult when the bulkheads are glued in place. I made a circular cutting compass to mark the circle, and prevent chipping prior to cutting out the ply with a jig saw.
5. I’ve drilled through the stem and false stem to allow me to fit an eye, for towing, trailer security or a bowsprit.
Blunders:
1. I glued both halves of the centreboard case together, had to start again
2. I made an incorrect mix of resin for the final coat whilst fibreglassing sole and garboard; patches didn’t cure. I scraped the off the uncured resin by wire brushing in acetone and cabinet scraper. Fortunately, the underlying coats cured.
3. I ordered Meranti ply during Covid lockdown from a local supplier. When I collected the sheets, I inspected the top two, but didn’t look close enough. The sheets were inconsistent, of poor quality. Moreover, and three-ply. Whilst I don’t think it will make a huge difference in the long term, three-ply is not nearly as strong as five, the face veneers are inconsistent, and there will be significant extra work in finishing and reinforcing the planks. I should have waited and paid the extra for five ply.
4. I’ve never been able to cut accurate gains in thin 6 mm planks. I shall reinforce inside the bow compartment with 100 gm tape.
So here we are, hull complete, waiting ready for turn over:)
URL: https://forum.mymorbic.uk/Notes-on-a-Morbic-Build-in-New-Zealand-tp414.html
I began building the Morbic in mid-July. I decided to complete the spars, centreboard, rudder and stock, before starting work on the hull. In my previous builds, mostly Oughtred designs, I have completed the hull, then discovered I have another month or so of work before I can go sailing.
So I made bird’s mouth spars from imported Douglas Fir. The timber was disappointing, developing splits and gaps within the glue up. Use the Duckworks calculator to caculate the dimensions of the spar strips.
It took about 30 hours to complete the boom, yard and mast. Out of interest, I glued the boom and yard using polyurethene glue, and the mast with epoxy. I wouldn’t use polyurethene again … messy, not much quicker than epoxy, and goes off quickly
I assembled the mast in two halves, so that I could add plugs and shape the slot for the halyard sheave. The plugs seal the middle of the mast, adding floatation.
In mid September, a friend who has a second-hand CNC cutter, cut the planks and girder from Vivier’s files.
These are excellent. The girder and planks fit together in most cases within + 2 mm and the time saving is huge. Strongly recommended.
The rudder and centreboard case took about 20 hours.
I use Titebond III to glue flat surfaces, such as doublers for centreboard and transom. It’s quick and easy to clean up. There is an old study from the US Forest Service that reports Polyamide glues are equally water resistant to epoxy. However, amide glues have poor gap filling properties so can only be used for well matched surfaces.
I laminated the false stem from Ash, two to three 3 mm layers at a time, and glued with Titebond III much easier than with epoxy.
I assembled the girder and molds at the beginning of October. Again, the Vivier CNC files are fantastic. The transom, longitudinal bulkheads went together in half an hour. I finished planking by 25 October. The only difficulty was, as usual, bending the the garboards into place, and cutting the gains to the stem. I’ve glued the planks with West System 105 + slow hardener.
Time spent to date, about 120 hours, including a round trip to Auckland to collect timber.
Notes:
1. Don’t use Polyurethene glue. Use Titebond III for well jointed surfaces, and epoxy when gap filling or filleting.
2. I lined the inside of the rudder stock with fibreglass to resist abrasion; that decreased the gap between the cheeks and the rudder cap no longer fitted. I’ve had to cut the cap in two and add a further layer of 2 mm ply to accommodate the rudder.
3. I cut additional clamping holes in the centre stem-leaf because I don’t have enough long clamps to laminate the false stem
4. Cut the holes for inspection ports in the longitudinal bulkheads in advance … it will be difficult when the bulkheads are glued in place. I made a circular cutting compass to mark the circle, and prevent chipping prior to cutting out the ply with a jig saw.
5. I’ve drilled through the stem and false stem to allow me to fit an eye, for towing, trailer security or a bowsprit.
Blunders:
1. I glued both halves of the centreboard case together, had to start again
2. I made an incorrect mix of resin for the final coat whilst fibreglassing sole and garboard; patches didn’t cure. I scraped the off the uncured resin by wire brushing in acetone and cabinet scraper. Fortunately, the underlying coats cured.
3. I ordered Meranti ply during Covid lockdown from a local supplier. When I collected the sheets, I inspected the top two, but didn’t look close enough. The sheets were inconsistent, of poor quality. Moreover, and three-ply. Whilst I don’t think it will make a huge difference in the long term, three-ply is not nearly as strong as five, the face veneers are inconsistent, and there will be significant extra work in finishing and reinforcing the planks. I should have waited and paid the extra for five ply.
4. I’ve never been able to cut accurate gains in thin 6 mm planks. I shall reinforce inside the bow compartment with 100 gm tape.
So here we are, hull complete, waiting ready for turn over:)
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