Boat getting stuck launching

[Ozwatson]

Looking for some ideas on how to solve a problem. I have a Quintrex 4.7 Bayhunter and it is getting stuck on the trailer when launching. The boat has a centre keel, about 2" high and I think it's getting caught on the centre rollers at the back of the trailer. The rollers are quite close together so the boat has to be dead centre for the keel to slip between them. Hopefully you can see in the photos. I usually have to rock the front of the boat side to side until it gets past the rollers.

I've thought of putting self centering rollers underneath but not sure they'd work with the keel setup. I've also thought of putting on a set of self align rollers but not sure if they will foul on the outer rollers at the back. Before I start throwing money at it I figured I'd get your thoughts.

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[RayLamp]

If it were me, I would ditch those rollers and put something like this on

http://www.ebay.com.au/itm/like/151340466176?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=107&chn=ps

[scottar]

You need to adjust the other rollers on the trailer so that the boat comes on and goes off straight. Just looking at the next set of rollers outside the centre ones, it looks like one or the other will always be catching a pressing and forcing the boat sideways. I had a Redco trailer with exactly the same set-up for 20 years with a Savage tinny with a keel without issue.

[Chimo]

Pull the centre back rollers out and put them back in with the bend facing forward not backwards.

Also ensure all the rollers on the trailer are carrying the same load.

Can you move / rotate each roller using the same force? If you cannot you probably need more rollers to share the load.

Set them all so the same force is needed to rotate each roller and the boat should fall off the trailer.

[Ozwatson]

Pull the centre back rollers out and put them back in with the bend facing forward not backwards.

Yeah, I have wondered whether that might be an easy fix. Might give that a try next time I have the boat off.

[astro66]

mate the center rollers are to stop the bow hitting the trailer...dont turn them around....either drop them so the boat only touches as it first winds on till its up on the next center roller back ...or swap them over but dont turn them around that will give you more room between them..or just move the winch post back a bit till the boat doesnt catch anymore....

[littlejim]

For mine the procedure was to loosen all the middle rollers until the boat was resting on the front and rear ones (set for the height i wanted) then tap up all the ones in between until they were loaded up a bit.

My great improvement came when I got rid of all the galvanised roller axles (many with rough dags of zinc galvo on them) and made up my own axles out of stainless steel rod.
Worked like a charm for years since.

[Ozwatson]

or swap them over

Understood - will try this first. Might give just the right spacing to sit between the ridges and keep the boat centred as it comes on. I know the middle keel roller isn't rolling so the boat just drags across it which probably doesn't help it centre. Would those self centering rollers work with this type of keel?

[MyWay]

I think your boat is to far forward on trailer, try to adjust front post(winch post) so boat hangs just one inch over the roller at back

[scottar]

If the rear rollers are put into any configuration apart from where they are now the bow will most likely hit the crossmember as you start to winch on. They are designed to be a rudimentary self centring type setup and are about the only way you can have them on a keel that is cut away as it approaches the transom. If you use any of the standard self centring type rollers on a spindle, they will not be supporting any weight once the keel runs past where the cut away begins. If the boat is moving away from centre either the position of the two rollers are not "mirroring" each other properly or other rollers on the trailer are out of adjustment or location in relation to the pressed strakes. The strakes will catch a roller edge and the hull will shift sideways as it comes up. If it isn't obvious as to where the problem lies, try getting a mate to slowly winch the boat on while you keep a very close eye on the keel in relation to the centre rollers. As soon as it starts to move sideways look for a roller that has just made contact or a pair (one on each side) that are not in the same relative hull position.

[Chimo]

Moving the winch post back is certainly worth considering too. Before doing so consider how the weight distribution is set. Do you have sufficient weight on the tow bar? Just how big an issue this will be will also depend to some extent on what you tow with. If you need to move the winch post you may also need to move the axle position if the weight distribution alters too much; again the tow vehicle may make this more or less critical depending what it is.

You need to be aware of the impact, or not, of changes you may make. If rotating the rear rollers is going to put the boat at risk of damage from the trailer then don't do it, mind you it didn't leap out as a major threat based on your pics.

[Fed]

I agree with scottar the outer rollers are pushing the boat sideways, just move them both to the left to centre the boat then give all the rollers a bit of grease, adjust the heights and try it out.
Probably have to move the outer ones at the front also.

[Horse]

If it was mine I would try a couple of things. Drop the rear centre rollers by 40mm. They should not be weight bearing and secondly replace the keel roller spindles with stainless or at least new gal ones

[Ozwatson]

Thanks for all the comments. Lots of things to try - will take it one step at a time and see how each adjustment affects the setup. A couple of comments on recent posts:
1. The winch post can come down a bit to move the boat back. It came loose one day on the way home and I think I have secured it a bit higher than it was originally so no problem dropping it down a bit.
2. Slight weight shift back shouldn't be a problem. Towing with a 4x4 and plenty of weight on the front currently.
3. If I do move the rear centre rollers I'll check the clearance to the trailer frame when pulling the boat on. If it's in danger of hitting I will move them back.
4. I have tried seeing why it is not coming on centred but with wind and waves moving the boat around as I'm winching plus the rear in the water it's a bit hard to tell.

Once it's on the trailer, should the weight mainly be held by the centre rollers or the side rollers?

[aussiebasser]

Being an alloy boat, it shouldn't have any side rollers it should have skids. The weight should be taken by the centre rollers, drop the middle wobble rollers at the back, they shouldn't be taking any weight at all, they're just for guiding the boat onto the trailer.

[Chimo]

People on here have different ideas about how alloy boats should be supported on their trailers. I have no opinion but was told by the manufacturer of my alloy boat who also sold the same boats to the govt dept I used to work for that all the rollers on the trailer ie keel and side rollers should bear equal weight and the the test was to have the boat ready for travel and at that point test that every roller was equally hard or easy to rotate. He was not keen on skids or bunks as adjustment was too limited.

After nine years of use my boat would fall on and off the trailer extremely easily.

As mentioned above I have no personal basis for saying this other than it is what we were told by the man who made and sold us the boats.

[scottar]

A typical "tinnie" trailer uses skids so as to support any weight (and there shouldn't be a huge amount) that is supported by the outside skids/rollers across the ribs - not point loaded onto the aluminium sheet by a roller in an area between ribs. That said, provided that there are enough rollers with even weight distribution, the weight is not excessive or the rollers align on areas of the hull that have a rib immediately behind them rollers are a perfectly acceptable solution. Problems (dints) can occur with outer rollers bearing large amounts of weight if the placement has them in the middle of two internal ribs and the only structural support is the pressings in the hull sheeting itself.

The strongest section of your hull in this type of alloy construction in relation to weight bearing is your keel. The side rollers are typically set up to stop the boat falling over.

[Chimo]

Scottar, you are correct but this highlights yet another issue that is the cause of the problem you identified.

A too large proportion of the trailers supplied with boats are inadequate for the purpose for which they are supplied.

Many new boaters have little idea and many retailers put together underdone packages.

We all get what we pay for. People need to know the score or at least need to know they dont know and seek advice before spending $s Thats what so good about this and similar sites, people can ask, gain a range of ideas and then make up their own minds.

The trailer supplied by Mackay Trailers for my aluminium boat had 29 rollers spread along the keel and under the hull. In 9 years of long distance country running to the coast with frequent need to drop wheels into the gravel because of the narrow country roads did any dints appear.

[scottar]

A too large proportion of the trailers supplied with boats are inadequate for the purpose for which they are supplied.

Many new boaters have little idea and many retailers put together underdone packages.


.

That right there is definately the unfortunate truth. I have seen some horrible examples over the years.