You only have to look at the workouts happening around boat ramps to understand most boat roller setups are wrong. You have to be crazy if you enjoyed huffing and puffing when launching the boat from your trailer.

Launching and retrieving should be an easy, professional operation. With some minor alterations and additions to your trailer, boating will be a dead set breeze.

Most manufacturers do not build trailers for their boats rather they source trailers their trailer suppliers range of boat trailers. There are a few boat manufacturers making their own trailers which is good news because these boats fit their trailers perfectly. 

Have a good read below and you will find the best setup for your boat.

THE GOLDEN RULES FOR POWER BOATS

• More boat rollers rather than less make your boat easy to launch and easy to retrieve.
• Do not grease spindles. Grease attracts dirt, grim, and organic matter that is in the salt water. Do not use zinc coated spindles, reasons follow.
• Stainless spindles are fantastic if you cut your own stainelss rod otherwise stainless can be a tad expensive. Use marine grade 316 Stainless. It's a great investment when it lasts forever.
• Galvanised spindles are far better than zinc spindles. I would not receommend Zinc spindles.
• Boat rollers fail for two main reasons (a) Rust expands the zinc spindles inside the roller bore and this causes rollers to split. Zinc will rust in time whereas Galvanised last longer or stainless steel spindles last forever.
• (b) Grease can harden which causes rollers to jam on spindles.
• Inspect rollers every two years if you are using gal and every year if you have existing Zinc spindles. Personally, I do not like Zinc spindles, go Gal and you will never regret it. Go stainless and you're a winner. 
• Use big rollers where the weight is located, usually on the transom. Use smaller rollers as the boat approaches the winch post so the bow is aiming nicely at the bow stop on the winch post.
• Remember, most of your boat weight should be on the keel. This will help centre your boat. If your boat is not centering right then drop your wobbles on one side 5mm. 

Boat rollers setup.

1. Your stern rollers should be large and suit the contour of your stern keel. A large flat or curved roller are the go on a tandem bracket. Most sterns would use a flat roller set up on a tandem roller bracket which is supported by a 6" two post assembly and bolted onto a twin post holder bracket. Both rollers will hold a major share of weight placed on your transom. Larger boat use larger rollers.
2. Your next roller will be situated about 1 mtr away and will probably be an 8" curved, again to match the keel of your boat. Unless you have a 50mm Keel strip running the length of your keel then go with a curved single roller on a flat or post bracket.
3. Towards the front of your boat you will either need a self centering or a keel roller. Remember that you now need to start centering your boat on the trailer in preparation for docking into the bow stop. Self centering rollers are useless down the stern unless your have retriever mates or spring loaded roller systems.
4. If you have skids, get rid of them. They do not allow your boat to roll off. I have never been an advocate of submerging your trailer to get your boat off. I admire those skippers who have put some thought into their boating and it is evident at the ramp where your skills are on display.
5. Well OK, skids are OK on some boats. Boats with flat bottoms and boats that travel a lot of miles to get launch should be using skids. Harder to launch sure but you just cannot trust wobbles and othe rollers not to rub through your hull over the long haul roads. Example: Mt Isa to Cairns trailers would be using wide skid mounts.
6. One of the big arguments for skids is surface area holding up your boat. A 2" wide skid at 6 foot long equals 120 sq inches of surface area under each skid. Problem is most skids do not sit flat under boats and in many cases the skid is either sitting on one edge or the skids has been installed without consider a tion given to the curvature of the hull. Skids will also mark your hull unless you have an unpainted aluminium hull. Wobble Rollers work fine and do not cause damage to hull but more importantly fit the curvature of the hull. Ok, so by now you've guessed I don't like skids.
7. If your boat already has skids or a combination of skids and wobbles then consider putting in some KEEL rollers to carry some of that weight. If your boat has skids only, then you will need some keel rollers.
8. IMPORTANT: Replace those skids with single, twin wobble or quad rollers depending on your boats weight. Years ago Jet Ski's were on skids, today you see most of them on wobble rollers. Long distance travelling require more rollers due to vibration of the rollers rubbing on your hull.
9. Replacing keel rollers is easy once your have selected the right rollers. Now put your boat back onto the trailer and install one wobble on one side of the transom so it fits hard up onto the hull. Get your mate to lift the other side of the transom and the bolt the wobble up onto the hull. Repeat the process for the other wobble further forward.
10. Now while you can rest the entire weight of the boat on the keel, it is best to shift weight onto the wobbles because the more weight you have evenly distributed on as many rollers as you think fit will cause your boat to roll off your trailer in an easy manner.
11. Always select galvanised or if you can afford it, stainless spindles. Zinc spindles can cause pre-mature rusting and splitting of those expensive rollers you have purchased. I have seen too many zinc spindles and brackets fail over time to even consider them.
12. TIP: Now this may sound funny, but when purchasing black or grey rubber rollers, smell them. If they smell like old burnt rubber then that is because they contain up to 10% re-grind material. Rubber is a mild smell and not a horrid smell. The re-grind component will cause pre-mature aging and will mark your boat.
13. Remember to have your bow hook in place when launching. It is not uncommon to hear about the boat coming off the trailer with a good roller setup.
14. With your new setup, your launching depth will be shallower. Look at your mudguard and see how far it is out of the water during your best launch. Your mental note will be handy next time you are launching the boat.

EXAMPLES

• Have you ever seen shark cats with skids running across the supporting beams on trailers? Wrong setup, 3 to 4 tonne of boat being launched and retrieved can be mighty dangerous stuff. 12" flat or curved rollers take very little engine power to launch and retrieve. I have had one of these beautiful boats and I can tell you that while it looks great at the ramp to see a big cat being launched and retrieved, the skipper is having kittens getting that 4 tonne monster back onto the trailer safely.
• Skids and winches do a powerful lot of work and place huge pressure in the U hook on the bow. My little ski boat has a U hook which now needs replacing because the trailer needs to be at an EXACT depth in the water for skids to work properly and it's real hard to judge exact depth every time. The ski boat get wobbles next time I am down at Lower Portland on the Hawkesbury. (Update: Ski Boat got wobbles. Should have done it years ago, what a difference)
• Finally, the worst thing you can see when launching boats is a skipper who has been given the wrong setup. Oh yes, manufacturers make mistakes because they design boats and not trailers. Their trailers are built by trailer builders so it is quite likely you do not have the best roller and bracket setup for your boat. So have a good look around your hull and understand how it works. Then you will be in a good position to make some small adjustments or additions to your setup.

The key to a good setup is 60% keel weight and 40% wobble weight. Once setup up, your boat will glide off the trailer.

I hope you find a few clues on how to improve your boating. Good luck.

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