DIY trailer

[J.P.]

hi guys. i need help. i built a plywood boat, which i temporarily carry on top of my van, and i can't use it much because loading/unloading takes a lot of effort. i need to round up at least 3 helpers just to load the boat and it sucks, so most times i just decide to rent a boat than bring my own. i want a trailer asap. buying a trailer is out of the question, in my area, they are too rare = too expensive.


i can't go ahead with the build because i need dimensions. can somebody with a simple trailer for a 14ft semi-V provide the measurements? if anybody can spare the time, i'd apprciate the numbers for A, B, and C in the drawing i attached. i wasn't able to include the height in my drawing, but i'd also need to know how much distance i have to put between the axle and the frame. i'll be using 13 inch wheels because the boat will be towed over unpaved roads. i searched the net and i can't find any trailer plan, so if you know any links it will be a treasure.

what material, size and gauge should i use for the frame? i have access to square tubing, C-channel, angle bar, and steel pipes. i just need a lightweight trailer. my boat is only about 70kgs with motor and fuel, would probably max out at 85kg once i can afford the biggest possible motor for it.

i have zero experience with trailers so i'd also appreciate any extra tips which might shorten my learning curve.

thanks in advance to everybody!

 

[Johny25]

I have a trailer for my 14ft V-hull that I will try to remember to pull measurements on tomorrow but here is a very cheap harbor freight one with measurements.

https://www.harborfreight.com/600-lb-capacity-boat-trailer-with-8-inch-wheels-and-tires-5002.html

 

[J.P.]

thanks johny!!!

it's a nice design, but i'm from the philippines.......a trailer like that would cost 3 times more here so i'll have to make one. any idea on the size and gauge of the square tubing used?

it kinda puzzles me how to fit a 14ft boat on a 12.8 ft trailer? the back of the boat with motor is left hanging?

i omitted the distance between fenders in my drawing. i already know it would have to be 50+ inches to fit my boat.

 

[Johny25]

Well the upright that stops the boat in the front of boat trailers are usually bolted on by large U-bolts to the neck of the trailer allowing you to loosen and slide to correct boat length. So a typical trailer can handle boats in several different lengths. I will get you measurements on min this afternoon and I will get you the steel tubing sizes : )

 

[gillhunter]

thanks johny!!!

it's a nice design, but i'm from the philippines.......a trailer like that would cost 3 times more here so i'll have to make one. any idea on the size and gauge of the square tubing used?

it kinda puzzles me how to fit a 14ft boat on a 12.8 ft trailer? the back of the boat with motor is left hanging?

i omitted the distance between fenders in my drawing. i already know it would have to be 50+ inches to fit my boat.

J.P. Here is a simple design that EZ Loader makes. It's all tubing and channel. Maybe you could build something like this? Don't know what gauge it is, maybe one of the guys on the site that doe's metal fabrication can help you out.

 

[earl60446]

I can't speak for the phillipines but around here where I live. There very often are small fiberglass boats that have outlived there usefulness (rotten wood, etc) for sale, these usually come with a usable trailer and sometimes a motor that still works and at a very cheap price. Maybe around $500 or so. Hard to get a motor and build a trailer for that. Just junk the old fiberglass boat.
Tim

 

[novaman]

A lot of the trailer owners that I see at our store (Metalsupermarkets), are looking for tubing to extend a tongue or make another crossmember. Most of the smaller frame trailers like You could use are made with 14ga. (.083 ) tubing . In your case if the lowest price material is 1/8" (.125) that would not be too thick. If the only thing available is metric try looking for something like 64mm x 38mm x2mm tubing or even 50mm x 25mm x 2mm. Those are roughly equivalant to our 2 x 1-1/2 x .083, and 2 x 1 x .083. If only square tubing is available use the 2" for the frame rails and about 2" angle for the crossmembers. Using the rectangular tube for the frame rails and the square tube for crossmembers, should be heavy enough for a boat like that. I would probably make the tongue out of a 2-1/2" square tube with 1/8" wall. If You have mig welding available, the thinner tube would be fine, but if only stick welding is available I'd say use the 1/8" wall tubing. If there's channel that is 3" x 4.1 lbs. per ft. , that would make plenty heavy enough frame rails also. These are just my opinions based on what I see in already made trailers. I hope this helps for materials. As far as measurements, I;d suggest turning Your boat upside down and measure distances the same way You did to get the 50" width. The tongue should extend approximately 36-48" beyond the actual boat length, to accomadate a bow stop and winch mount, and still leave plenty of room to access the rear of the tow vehicle. keep us posted and show some pictures of the boat and what You build to haul it on.

 

[J.P.]

I can't speak for the phillipines but around here where I live. There very often are small fiberglass boats that have outlived there usefulness (rotten wood, etc) for sale, these usually come with a usable trailer and sometimes a motor that still works and at a very cheap price. Maybe around $500 or so. Hard to get a motor and build a trailer for that. Just junk the old fiberglass boat.
Tim

recreational boaters are a rare breed in my country, so their old toys are even more rare. even the small tri-hulls many americans call junk being sold for the equivalent of over $1000, that's without a trailer.


thank you for the replies. i'm more confident now to go ahead with the build. i have decided on channels and angle bars because i can paint those properly. one more question, is it ok if i just estimate the positioning of the axle? if i'm making a 16ft trailer, i plan to put it about 4ft from the back.

i will definitely share the result of my trailer project. click my signature to see the boat build.

 

[Johny25]

You want to make sure the center of gravity is in front of the axle so it is not pulling up on your trailer hitch, you want it pressing down. Also you don't want to unhook it and it lift up and crash your motor to the ground. My axle is at about the 2 ft mark from end of trailer.

 

[J.P.]

yeah, i thought placing the axle 3/4 of the way from the front is enough to put the weight forward. i'll place it as far back as possible. i can't do 2ft bacause i'll be using scrap leaf srpings, which are long compared to real trailer springs. worst case scenario, i'll have to add some ballast to the front.

 

[Johny25]

As long as you don't have a giant outboard hanging off the back you should be fine with it at 3/4 of the way : )

 

[GTS225]

yeah, i thought placing the axle 3/4 of the way from the front is enough to put the weight forward. i'll place it as far back as possible. i can't do 2ft bacause i'll be using scrap leaf srpings, which are long compared to real trailer springs. worst case scenario, i'll have to add some ballast to the front.

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You don't want it too far back, either, as then the tongue weight will get excessive, and drag the rear of your towing vehicle down. I've built two trailers, one was 20' (6.2M) long, and I placed the axle centerline at 57% of frame length on the 20-footer, and 60% on the 16-footer. These two were intended for towing cars, though.
For what it's worth, in trailer design, the 60% rule is average. For a slightly lighter tongue weight, move the axle(s) forward slightly.

If you can rob an axle and springs out from under the back of a front wheel drive small van, then that will give you an axle that you can gets parts for. I built a small 12-foot trailer using the axle from under the rear of a pre-'93 Dodge minivan. The main tube is steel tubing, and is easy to extend, (if needed), with 2" black pipe. Just cut it in the center, slide in an appropriate length of black pipe, and weld away.

Roger

 

[J.P.]

thanks roger. maybe i'll assemble the frame with tongue first, put the boat and motor on it, then try to find a good balance point for the axle before welding the hangers.

front wheel drive minivan, that's another rarity here, or at least a rarity in the scrapyards. my axle came from a 1989 mitsubishi mirage, paid $35 for it, i'll widen it by using lengths of heavy round and angle bar.
i'm still tying to find smaller springs, probably from those tiny daihatsu or suzuki "micro" vans.

 

[GTS225]

thanks roger. maybe i'll assemble the frame with tongue first, put the boat and motor on it, then try to find a good balance point for the axle before welding the hangers.

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Not an unreasonable plan. Keep in mind that you do want some weight on the tongue. (My guess is somewhere between 50-75Kgs.) Something that you can still lift by hand, but if it happens to come loose from the towing vehicle, will drop tongue-down as a sort of safety device.

front wheel drive minivan, that's another rarity here, or at least a rarity in the scrapyards. my axle came from a 1989 mitsubishi mirage, paid $35 for it, i'll widen it by using lengths of heavy round and angle bar.
i'm still tying to find smaller springs, probably from those tiny daihatsu or suzuki "micro" vans.

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Well, I didn't figure you folks had any of our bigger "minivans" over there, but was thinking along the lines of the Daihatsu or Suzuki. Aren't those front wheel drive? (If not....my mistake, sorry.)
Might I suggest; Look for another axle, or at least the spindle and wheel assembly from another '89 Mirage. Keep it with the trailer at all times, with the needed tools to swap it out. It might save you a ruined trip, should you have a bearing go bad unexpectedly.

Roger

 

[J.P.]

American vehicles are relatively young here, and they are well maintained, so there's zero chance of me finding one in a scrapyard. The tiny vans from japan that we have here are 4 wheel drive. some diy trailers i see do make use of rear wheel drive axles, but i don't like the look of the bulging differential case and i think it just adds unecessary weight. I checked many local front wheel drive vehicles to see a good axle donor, only the old mirage has both rear wheels connected together by a horizontal bar that i can use to mount a leaf spring.

I don't think i have to buy a spare parts, maybe just a pair of bearings. I used to own that model of mirage, so i have experience with its wheel bearings. the design is very simple to maintain, just remove the center nut and the hub pops right off to expose the tapered bearing. replacement may take extra effort to remove the race that's force fitted into the hub, but i've done it before with a hammer and a big flat screw driver. the center nut though is huge, so i'd have to carry the BIG socket wrench.

 

[J.P.]

finally started on my build.
at first i wanted a very light trailer, but i took into consideration the possibility of an "upgrade", so i decide to use materials which are slightly more robust than required on my current boat.

frames are combination of 3 inch channel and 2.5 inch angle bar (both 4mm thick). i had to buy whole spans of 3 inch channel, so i have enough left for a 10ft tongue, but my coupler is 2.5 inch. so it would look so much better if i will use a 2.5 inch square tube. i'm confused, i'll save money and i get to paint everything if i use the channel that i have. on the other hand, if i use a square tube, it will look better and probably be stiffer, but cost me more and i can't properly paint inside it. what do you think?

my over all length is 16ft, my boat is 13ft. is that a good fit or should i put in a longer tongue?

 

[J.P.]

i edited the subject since i want to continue my DIY project here instead of starting another topic.

everything that has to be welded is in place and primed to prevent rust. other hardware like winch post, spare tire mount, and brackets for the bunks and guide-ons will be bolted on or u-bolted.

has anybody had experience with channel for a trailer tongue? i'm having second thoughts about the structural integrity. everybody i asked insisted on square tube, but i alreay made mine using 3 inch channel(big mistake to build first before asking). vertically, it holds up well even if i stand on it, but it kinda wobbles from side to side if i shake it. is this bad? i can redo the tongue, but i don't want to unless it's absolutely necessary.

 

[DaveInGA]

J.P.,

Answers and comments in red in the quotes below. I checked out your boat build. That was some beautiful work. I've seen similar jon boats built here in the states and fished them as a kid. I was seriously considering building one for myself, but couldn't find a size my wife would accept and get into with me, so I ended up going with a bass boat to get her into it. Would love to have a light weight jon like the one you've built so I could hit the smaller lakes. I'm a big fella though, so I'd have to have a wider, longer one.

frames are combination of 3 inch channel and 2.5 inch angle bar (both 4mm thick). i had to buy whole spans of 3 inch channel, so i have enough left for a 10ft tongue, but my coupler is 2.5 inch. so it would look so much better if i will use a 2.5 inch square tube.
How about using some of the 3" channel and "stepping" it down in size?

I'm confused, i'll save money and i get to paint everything if i use the channel that i have. on the other hand, if i use a square tube, it will look better and probably be stiffer, but cost me more and i can't properly paint inside it. what do you think?
Seal up the ends of the square tube with some of the extra steel you have. You'll have to cut out square sections to use as "patches" to weld onto and close off the ends of the square tubing. But if you do this, you'll have to run your wire outside the tube, not a good idea. Generally speaking, the square tubing is what's used in boats here in the states. The inside is not painted, even in the coastal areas. With proper drainage, the tubing lasts a lifetime in most cases.

my over all length is 16ft, my boat is 13ft. is that a good fit or should i put in a longer tongue?To get an idea of if your tongue length, look at the tongue to main trailer length proportion in most pictures where you know the boat length. Generally speaking, if you have room to store it, a longer tongue is better.

In my sig, you'll see a link to a boat rebuild I'm doing. On page 9 is my trailer. The boat is 17 feet in length and the trailer was custom made for the boat. The tongue on it is what I would consider the minimum length for a tongue and what I would lengthen if I had a larger garage and I've been debating a hinge type tongue. If you need measurements, PM me and I'll be glad to get them for you to give you an idea of tongue to body ratio.

everything that has to be welded is in place and primed to prevent rust. other hardware like winch post, spare tire mount, and brackets for the bunks and guide-ons will be bolted on or u-bolted.
The dimensions of these items and what they bolt to will somewhat determine what size tongue you need.

has anybody had experience with channel for a trailer tongue? i'm having second thoughts about the structural integrity. everybody i asked insisted on square tube, but i alreay made mine using 3 inch channel(big mistake to build first before asking).
If you've already made it, then there's ways to fix or modify it. It's steel and you can weld on it.

vertically, it holds up well even if i stand on it, but it kinda wobbles from side to side if i shake it. is this bad?
Sounds like if you run into trouble, it will bend at the tongue or possibly other areas. I have a suggestion and I'll list it in a second.

i can redo the tongue, but i don't want to unless it's absolutely necessary.
If I'm into a project and I've already built something, I try not to go back and replace an entire section if I make a mistake. In your case, you've built with channel. But you have some extra steel left over. Here's what I suggest:

1. Using the left over steel, cut it up into sections that are the appropriate width to weld onto the "open" side of your channel. It would be a lot of work to weld the entire tongue or frame of the trailer, but it would be worth it. If you don't have enough leftover material to do that, you can put "patches" or "reinforcement" at critical areas, such as where the tongue attaches to the trailer, the middle of the tongue and next to the coupler.

2. Additionally, you can use any other leftover steel to reinforce the rest of the trailer by welding reinforcement patches across the channel on the open side.

The ideal solution would be to have used square tube and the second most ideal would be to close off as much of the open side of the channel as you can. But if you can't do all of it with the material you have, do as much as you can and put reinforcements in the most critical areas.

Hope this helps,

 

[J.P.]

Thank you for taking the time to answer in detail. I'll try to do as much reinforcement as i can, then test the rig, i hope it holds up good.
If i don't like the results, i'll replace the tongue with square tube.

 

[J.P.]

I decided to follow good advice and was going to change the tongue to 2.5inch square tube, but as it turns out, it's not available(in my area) in the size i need. The nearest sized square tubes in my area are 2 and 3 inch, but both have very thin walls, so they're not gonna work. Then, i saw pile of 3 inch flat bars in the perfect thickness. I spot welded it along the open side of the 3 inch channel and now my trailer tongue is a 1.5x3 inch rectangular tube. Coupler and tongue still looks very awkward, but it's a lot stiffer now.

I also fabricated trailer stand with a caster wheel, it swivels to parked and towing position. I don't think the "jack" feature is required since my rig is very light. But i'd buy a proper trailer jack if given the chance.

things to do:
1. Bunks and guide-ons
2. Winch post/bow stop
3. lights
4. Transom saver
5. winch
6. keel rollers
7. undercoat the springs/axle and hubs

trailers are deceptively simple to look at, but there's a lot to be done.