C17 in New Zealand.

To help other builders, please list the boat you are building in the Thread Subject -- and to conserve space, please limit your posting to one thread per boat.

Please feel free to use the gallery to display multiple images of your progress.
TomW1
Very Active Poster
Very Active Poster
Posts: 5844
Joined: Sun Apr 19, 2015 10:57 pm
Location: Bryson City, NC

Re: C17 in New Zealand.

Post by TomW1 »

One Way Traffic please do me a favor and do not use rollers unless they go directly under the stringers. They are notoriously know to form themselves to the bottom of the boat leaving dimpls where they rest against it. For the C17 it would even be better to use planks with carpet or the new glass type glides. Rollers are not needed for a C17 and can do more damage than good. If you insist on them put them in the proper place.

Good luck with your decision. Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

OneWayTraffic
* Bateau Builder *
* Bateau Builder *
Posts: 1662
Joined: Sat Jan 10, 2015 7:13 pm
Location: New Zealand

Re: C17 in New Zealand.

Post by OneWayTraffic »

Tom nearly every boat in NZ sits on a roller trailer. They do not cause a lot of issues. Bunks are generally a non starter in NZ due to the ramp conditions we have here. The boats are built to handle it. The typical aluminium trailer boat here has a hull thickness of 3/16" to 1/4" for bigger boats. I don't know exactly the hull thickness of glass boats, but every single one in NZ sits on a roller trailer. If it didn't work it wouldn't work. But it does so it does.

I know that it's better to spread the weight. The keel in my boat is built to spec and then has a skeg on top, glassed in with aluminium flat bar. This will hold the majority of the weight. There are skids ( metre long bunks with plastic skids) at the back supporting the transom area. I will try to put these near or under the stringers. I have two wobble rollers further forward to provide extra side support. They will not hold a lot of weight.

I did do my Maths on this; I am confident that this is more than sufficient, even on NZ roads.

OneWayTraffic
* Bateau Builder *
* Bateau Builder *
Posts: 1662
Joined: Sat Jan 10, 2015 7:13 pm
Location: New Zealand

Re: C17 in New Zealand.

Post by OneWayTraffic »

This picture shows the setup. The weight distribution would be at least half on the stoutly built keel and most of the rest on the rear skids. I might have made the skis longer but they wouldn’t make full contact along the length anyway. I might make longer ones later. The rollers are not in this picture but are positioned further forward under the third crossbar. They are adjustable to only stabilise the boat side to side. No real weight in use.

The keel rollers are unlikely to dimple the aluminium that is glued to the skeg. The keel layup is 5 layers glass, 6mm ply, four layers glass,18mm skeg then two layers glass and 3mm flat bar. Estimated weight per keel roller under 50kg.

If I’m not happy with it adjustments will need to wait until I have the boat on the trailer. I might make a pair of longer UHMWPE covered skids for the back but want to get it on the trailer first.
Attachments
70154E26-C61B-4075-AAEC-F495BF50E2B8.jpeg
7A0D5646-4518-43B5-8F60-21CA70215D68.jpeg

Fuzz
* Bateau Builder - Expert *
* Bateau Builder - Expert *
Posts: 8920
Joined: Tue Aug 02, 2011 4:23 am
Location: Kasilof, Alaska

Re: C17 in New Zealand.

Post by Fuzz »

I have seen you speak about the boat launches there a couple times. I am just wondering what is different there? I fully understand that local conditions often times dictate how things are done. Most folks do not have to deal with 30 foot tide ranges and the current they bring but this is normal for me.

OneWayTraffic
* Bateau Builder *
* Bateau Builder *
Posts: 1662
Joined: Sat Jan 10, 2015 7:13 pm
Location: New Zealand

Re: C17 in New Zealand.

Post by OneWayTraffic »

Tidal ranges are one thing. There are several places in NZ with enough of a range where you can launch into water but the ramp will be completely dry at low, and you are dragging the boat over mudflats. Other places without that tidal range (sea or lakes) have no built ramps at all, you just back the car into the water. Anyway if you buy a boat in NZ, 95% of the time it will be on a roller trailer. You can't even get a bunk trailer in larger sizes (over a 14' boat say) unless it is custom built for the boat, or you take off the rollers and build your own bunks. Many older boats in NZ have keels built very strong and were designed to sit on the keel on the trailer. My keel roller trailer is 40 years old, so I gave it a complete rebuild. It seems the older trailers last longer than new ones. Many modern trailers have box section, which rusts from the inside out in under 10 years if you don't look after it right.

I think some of this is tradition; I see no reason why even a heavy glass tub will not slide right off two plastic covered skids on a decent slope. The other part of this is that since most boats in NZ are trailer launched every day rather than left at a dock, and we are a small country where people may trailer to either coast, launch from a variety of places with different tidal conditions and our few trailer manufacturers need to design for a wide variety of boats, and wobble rollers are easier to setup for a hull, wobble rollers are the norm. They also make it much easier to offload the boat onto the lawn for DIY repairs.



Anyway my trailer is best described as keel rollers with skids. After getting the trailer I modified the build of the boat to suit. The keel can handle the load, the current donor boat rolls right off and cranks right on. I will check and possibly rebuild the skids once the C17 is on the trailer, as early as this summer.

TomW1
Very Active Poster
Very Active Poster
Posts: 5844
Joined: Sun Apr 19, 2015 10:57 pm
Location: Bryson City, NC

Re: C17 in New Zealand.

Post by TomW1 »

I hope you make September that is the beginning of your Summer. Enjoy your boat you have done a wonderful job on her.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

User avatar
BarraMan
* Bateau Builder - Expert *
* Bateau Builder - Expert *
Posts: 2164
Joined: Tue Dec 11, 2012 3:44 pm
Location: Australia

Re: C17 in New Zealand.

Post by BarraMan »

I have a somewhat unique perspective on this issue as my boat has been on both a bunk trailer and a roller trailer! 8O

It started out on a bunk trailer - typical USA style alloy trailer with rubber torsion bar suspension and wide plastic bunks of some sort. It was custom fitted to the boat - so the bunks sat directly under the stringers. There was no support under the keel. It was essentially drive on/drive off and OK for launching and retrieving provided you sank the trailer sufficiently to take some weight off the bunks. However, the bunks did do some scraping damage to the bottom of the boat which was: 2 pack polyurethane top coat, over 2 pack polyurethane undercoat, over epoxy/graphite, over multiple layers of glass cloth.

Image

One trip to the Northern Territory destroyed the suspension on that trailer - so it was replaced with a custom built alloy trailer with roller/rocker spring suspension. The builder talked me into a keel roller ladder and support rollers that were also aligned with the stringers.

This trailer is easy drive on/drive off and a Boat Catch makes it easily handled solo. So I can rock up to a boat ramp in most conditions and quickly launch or retrieve a 22' boat solo. The keel rollers a closely spaced and seem to support the hull well. The side rollers just keep the boat level and don't carry any significant load. The keel of my boat has at least 16 layers of 12 oz biaxial glass cloth (9 on the outside and 7 on the inside. Before each big trip I get under the boat and inspect the bottom of the hull and keel and tap it with a small hammer to check for any weakness. The boat has now done about 25,000 miles on this trailer and many many launches and retrieves. It has nil damage to the hull that I can detect.

So far I have not found a similar pic of the roller trailer - but I’ll keep looking! :D

Essentially the same as this - with red rollers!

Image
Last edited by BarraMan on Tue Sep 14, 2021 5:03 am, edited 3 times in total.

OneWayTraffic
* Bateau Builder *
* Bateau Builder *
Posts: 1662
Joined: Sat Jan 10, 2015 7:13 pm
Location: New Zealand

Re: C17 in New Zealand.

Post by OneWayTraffic »

Thanks for that Lee. That is pretty much how I plan to support my boat, which weighs a lot less than yours. The keel is pretty much the strongest part of any boat, and is an easier target than lining up on stringers exactly. Got a picture of the trailer sans boat?

OneWayTraffic
* Bateau Builder *
* Bateau Builder *
Posts: 1662
Joined: Sat Jan 10, 2015 7:13 pm
Location: New Zealand

Re: C17 in New Zealand.

Post by OneWayTraffic »

Major milestone today. Just got it in while the sun was still shining and warm. Weather change this afternoon so I’m inside with a cup of tea and waffles looking at the wind and rain come in.

I was surprised at how fast that foam kicks off once mixed.

I’ll have some muffin tops to trim next weekend. Then off to get more plywood and get the sole on.
Attachments
16737597-78BF-40C9-A951-4AB5133404B3.jpeg

Fuzz
* Bateau Builder - Expert *
* Bateau Builder - Expert *
Posts: 8920
Joined: Tue Aug 02, 2011 4:23 am
Location: Kasilof, Alaska

Re: C17 in New Zealand.

Post by Fuzz »

Is your foam blue or is it the light coming through the tarp that makes it look that way?
Be happy about a little wind and rain, at least you are not looking at f@#%&ing snow :cry:

Post Reply

Who is online

Users browsing this forum: No registered users and 11 guests