Boat on trailer positioning advice

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suffolktim

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Hey guys...

Finished re-building my trailer for my new fishing boat, an IP14....finding it hard to get the boat positioned well on the rollers and pads, and there is an awful lot of bar foreward of the winch post. The double rollers are fine, with both sets rolling inside the bilge runners. The pads however arent ideal, with half the pad under the bottom of the boat, but the other half in thin air, as the bilge runners run along the middle of them.

The last two rear rollers dont touch at the moment, but thinking of padding them out to raise them.

I am slightly concerned by the long section in front of the winch post, and there seems to be a slight amount of flex when you pich up the trailer from the hitch - which I assume would go if I moved everything forward, including the axle (which can be moved) - what do people think of this idea?

Sorry for all the questions!

Cheers!





 
I'd look at lifting the front of the boat to drop the keel onto the aft two rollers rather than the other way round, it may be easier to recover.

I think I would prefer the two rollers further aft too but I'm no expert. It just looks easier to recover but supporting the hull for transport is another consideration. Most of the weight should be on the keel though, the rollers, and the rests on the axle should be just to keep it level.

How much nose weight do you have? You need some for stable towing, certainly on a bigger boat. I have loads of nose weight in my trailer, I can only just lift it, so it's good to tow, but it wrecks jockey wheels if you aren't careful.

I haven't used a boat like yours but had a trailer with a tail for a Mirror and it was a pain compared with the one that stopped at the axle. The aft roller put lots of stress on the hull compared with resting on two pads and rocking it up onto the keel with the shorter trailer.

Hopefully someone with more experience with a boat/trailer like yours will add words of wisdom.
 
First question is are you going to transport the boat with engine attached. If so fit the engine as it represents a major aft weight.
As said you need a lot of draw bar weight. 10% of total mass is a good figure. This will make for good towing stability.
You adjust the draw bar weight by moving the wheels or by moving the winch post forward.
I think the boat has some curve to the keel from front to back. If so it would not be surprising with the aft roller not contacting when in place. It's main job is in launching retrieval. However if keel is essentially straight then yes all rollers should take some weight. Raise the front rollers. Any slope of the boat stern down when in place will aid launching and recovery.
The trick is as said to lower the side support skids/rollers so that the boat can rock from side to side a little. Then get all keel rollers taking their share of weight. I think you could usefully have more rollers in the centre/forward area of the keel.
Then finally raise the side skids/rollers to just take out the rocking from side to side. But not taking weight.
The side rollers may perform a useful role as the boat is retrieved to centre the keel on the rollers but should not take weight when boat is in place.
Any excessive pressure on the hull can cause damage to the hull on a long drive. The keel however will be strong enough to take the pressure.
lastly try launching and observe carefully on retrieval just how the rollers work and you hopefully can get it all working well. good luck olewill
 
The keel seems to have a curve to it, so the rear rollers will not make contact when the boat is loaded. I would leave that as it it.
The boat needs to go somewhat further forward, not much but a few inches so the transom is more or less level with the back of the trailer.
You'll need to fit the engine if you intend having it fitted when trailing the boat. Having fitted the engine, use some bathroom scales under the jockey wheel to see how much nose weight you have. You need twenty to forty kilos. Leaving the winch post in position, move the axle fore and aft to adjust the nose weight.
The pads are positioned at right angles to the length of the boat at present. I'd turn them through 90 degrees so that you can get their whole length against the hull.
 
The pads should be oriented fwd/aft rather than transversely. As has been said, they exist to prevent the boat rocking on the trailer rather than to support the weight. If you are concerned about the bend in the drawbar, you could reinforce that part by clamping another length of square section underneath it. Moving the boat forward will make the bend worse. Adding the engine to the rear of the boat will lessen the drawbar weight. Depending on what car you use to tow, the pendulum effect of the engine will increase the tendency of the trailer to snake. Moving the boat forward will reduce this.
 
I am a qualified engineer and sailor and have built several boat trailers from scratch over the last few years for boats from 3.6 metres through to a new trailer for my 7.8 metre trailer yacht.
Your trailer is simple to adjust as most things just bolt on.
My advice is:

1: clamp the axle over the keel of the trailer instead of under it. As it is, the boat is sitting very high.
This will lower the boat by about 100 mm making it easier to launch and retrieve
You may need to space the rollers a little to ensure the keel of the boat doesn't impact the axle, but worth doing.

2: be aware that the steel keel of the trailer is quite flexible as it is at present, so as you drive down the road the load of the boat is actually only going to be supported by the two rollers either side of the axle. All the other rollers may assist with launch and retrieval, but will not be assisting at all when you hit a pothole at 59 mph. This is OK, the style of boat you have should cope with this no problem. It is best though if the rollers on either side of the axle are at the airy points (https://en.wikipedia.org/wiki/Airy_points ) with the center of the airy points being the center of gravity of balance point of the boat.
This sounds a lot more complicated than it actually is. Find the balance point of the boat in the configuration in which it will be on the trailer and space the rollers 0.5778 x total length apart. i.e If the boat is 5 metres then ideally the two rollers would be 2.887 metres apart. The worst thing you can do is have a roller directly on the axle as there will then be the single point of contact supporting the boat every time you go over a bump which has the effect of trying to break your boat in half!

3: As Duncan said: adjust the axle for a draw bar weight of 20 - 40 kg - with the motor on if that is how you will tow it.

4: i assume you have a light board that hangs on the transom. In that case the
actual length of the trailer is immaterial and as long as it can carry the afor-mentioned rollers, shorter may be easier for launch and retrieval.

5 As said, the side pads are 90 degrees out

6 I would shorten the draw bar so that the boot or tailgate of your towing vehicle can be opened without obstruction and not much more.

In your case i would start by bringing the winch post forward, then bring everything else forward to meet the above needs and then cut off the excess trailer keel.
Good luck.
John
 
Re the rear roller not touching the keel.

do NOT raise the front of the boat, you want that as low as possible for launch and recovery, so instead raise the rear roller.

It takes a lot of time and measurement to get a trailer right for a particular boat. Mine was hideously wrong so I took lots of measurements ans while the boat was in the water fir the first season replaced all the rollers in new positions. Even then it still needed some fine tuning.

I would move the drawbar backwards, i.e keep the winch post in the same position with respect to the axle but in effect shorten the drawbar and have more sticking out beyond the back of the boat

Re the pads, I would move them. Unfortunately that's one bit that is not on adjustable clamps to you will have to re drill the axle bar.
 
duncan99210 said:
....
The pads are positioned at right angles to the length of the boat at present. I'd turn them through 90 degrees so that you can get their whole length against the hull.
Click to expand...

The side pads are currently working on the bilge keel/rubbing strake. That distributes their force into the structure of the hull.
They should just be steadying the hull not taking significant weight when static.

Nose weight on the hitch is important.
Something like 10% of the trailer weight but not more than 70 or so kg or less than about 20 seems to be a fair guide?
Too heavy affects the car and too light causes the trailer to weave. Nasty!
 
WOW!! - what a response! Had a busy weekend, but been looking forward to sitting down and thanking you all for all of your advice!

First of all I plan to trail the boat with no engine on the back, and very little in the way of gear inside it, so it's pretty much how it will be set up for trailing in the initial pictures.

I Will hook the trailer up to the car, and adjust the winch post, as suggested, so it's just clear of the opening boot. This is how the caravan I take the kids away in is set up, so it will definately help to give me confidence! It seems that I will have to move the axle forward, as also suggested, and I will ue the bathroom scales trick to keep an eye on the nose weight when I do this.

Just out of interest, and as somewhere to start - is there a rough guide to how far back on the boat the trailer wheels should be level with? I thought I could set it up to the "ideal" distance, and then work from there if the nose weight wasn't right.

I will move the pads through 90 degrees - but was wondering, after reading about it just being a support, if I should move the pads so that they are running above or below the bilge keels?

I know that there is likely to be several feet of trailer left over after I move everything forward, and I also note the suggestion of cutting off the remaining trailer keel aft of the boat....is this essential, as I am planning sometime next year to buy an orkney longliner or similar, and would love to have the extra two feet in reserve for that.

Again, thank you all so much for your fast and detailed responses! This is a good example of forums like this coming out on top in knowledge sharing!

Cheers!

Tim
 
The side pads will need to stay at right angles if they are to support the bilge keels. However if you do turn them fore and aft they may fit inside or out side the bilge keels and so help force the boat into the centre of the trailer when retrieving.
Re the draw bar flexing. I had a trailer once with a telescopic draw bar. ie another square tube just fitting inside the main draw bar. it was actually a box trailer which got a longer draw bar to take a small catamaran. However the system can enhance launching and retrieval by allowing the trailer further into the water before the car gets to the water by perhaps 1 metre. It would also stiffen the draw bar when retracted and when extended make backing easier. Probably not a concern with your already long trailer.
I question ProDave's comments not to raise the front of the boat. Indeed I would suggest you do away with that block of steel which raises the hitch hence lowers the front of the boat. When launching the slope of the hull can aid in getting it to roll off and having the stern closer to the water means it will start to float earlier so aiding both launch and recovery.
Perhaps I am missing something in Prodave's comment. So I stand ready to be educated.
I do agree that any change of axle /springs to get the hull/axle keel lower to the ground will also aid launch and recovery.
good luck olewill (36 years owner of 21ft TS)
PS square steel tubing is horrible for a boat trailer. My draw bar parted after about 2 years from new due to salt water rusting the square tube from the inside. I now I regularly fill or at least coat the inside of the square tubes with old engine oil. Messy but effective. (I hope)
 
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You see lots of people towing boats with plenty of drawbar forward of the boat like that.
It's quite helpful when retrieving.
How much is it flexing?
If it is really excessive, is the tube section too thin? Rusted inside?
It should only be carrying the noseweight, the area nearer the axle will be more stressed.
Boat trailer do flex a lot, it's quite scary to follow an empty one sometimes.
Excessive length of trailer behind the boat is not great, but a foot should not matter.
If you want to get a longer boat in the foreseeable, I'd live with the longer drawbar.
If the spine section is not up for that, it's not up for the heavier boat either?
As a starting point, your boat on the trailer doesn't look wildly wrong to me, but I'm used to dinghies where you get some nose weight from the mast hanging over the front...

I'd expect the side pads to be fine just inside the bilge keels, but being used to lightly built dinghies, I'd prefer them under the keels.
Basically every bump will twist the trailer and try to punch the side pad into the hull.
 
Without having actually seen the trailer my immediate thought is to get rid of that rear roller and box section supporting it completely if possible. I can imagine that taking chunks out of your bow as you try to recover your boat if it's not pretty calm. Either that or some kind of guide to stop the boat moving sideways as you recover it on to the trailer.
 
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