How to size a trailer for a boat??

tractorboy

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Jul 1, 2010
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I pretty much KNOW my trailer is too big for my boat. IS there any information out there were I can properly know what size trailer to get for my boat. MY BIL is the orig. owner and has bragged that is is the smallest boat that will fit on that trailer...and it does fit and tow nice. The problem is that the boat sits too far UP on the current Roller trailer. At the docks whenever we go I have to go down the ramp a couple of times and slam on brakes to get sucker to roll/drop off. and when putting back on I basically have to winch it up onto the trailer with the strap like 20'. Im trying to get my trailer info now but its a 91 sunbird swl 207 so its basically 21' and about 3500 lbs roughly. My touch is way long and the uprights for the bow stop is PAST the back there the trailer branches out for the sides from the tongue......

I can lower the boat any on the trailer and the gun walls are about 1.25" above the fender. Widening the rollers doesnt get it sit lower either. It tows fine Im more concerned about high she sits and properly and safely getting in and out of the water. It FALLS into the water when I launch it. When I have a dock it was once or twice a year but we are not docking anymore and I need to know what size trailer. she how a big teak bow platforms that extends out making it say 20.7' but the boat is a 19' I think.

Any help greatly appreciated.
 

LippCJ7

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Re: How to size a trailer for a boat??

got some pics?

As in a BUNCH
 

smokeonthewater

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Re: How to size a trailer for a boat??

general rule of thumb is that the overall trailer length should be 10% more than the base boat length not including added swim platform or bow pulpit.... This is just a starting point..... Of course there are other measurements.... on some trailers the bunks aren't adjustable so they need to match up too.
 

tractorboy

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Re: How to size a trailer for a boat??

I will get a BUNCH OF PICS...as im sure that will help.....maybe I make it a BUNK trailer??

OK...LOOK FORWARD TO IDEAS and what not. trying to find info on trailer...a karavan....only have VIN ..need to look up and see where model # might be.

Thanks
 

tractorboy

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Re: How to size a trailer for a boat??

I will take more...I know I have more of the trailer last time I was trying to figure this problem....I just cant find them all so I will take more.

Side of Trailer.jpg

Im told that the boat and trailer are matched as far as weight. According to the dealer out of state that sold my BIL the trailer. But altimately I guess my problem is she sits way high....I will get pics but maybe if I convert bunk..I dont know. Really need to get to sit lower. The dock is a bear to winch that thing all the way back onto the trailer with the wheels at the edge of the dock in the water. trailer is submerged all the way.
 

NYGiants

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Re: How to size a trailer for a boat??

are you using an electric winch?
 

smokeonthewater

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Re: How to size a trailer for a boat??

Hard to tell in the pic but can you move the roller beams out from center.... If you can, that will lower the boat.
 

tractorboy

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Re: How to size a trailer for a boat??

It does not lower much moving the rollers outward toward the outside ends as the "v" sorta flatish. I think I need to convert to bunk. I have taken ALOT of pics hope it helps. I have a lot of room to LOWER and the gunwall to V is a good 12 above the trailer fender. Most pics I see of boats trailered that area is INCHES from the fender. Here is my set up..hope this helps
DSCF4390.jpgDSCF4367.jpgDSCF4368.jpgDSCF4369.jpgDSCF4370.jpg
 

tractorboy

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Messages
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Re: How to size a trailer for a boat??

does not want to allow me to upload more pics but I have more..and will try later. But I think my only option to lower say 10" is go to bunk. is 3200 or more lbs too much for a bunk trailer. I looked at all the parts for karavan trailers and no lower beams. I think I might gain an inch reversing the rollers if possible as they curve up but....
Do I need keel rollers?

Todd
 

tractorboy

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Re: How to size a trailer for a boat??

are you using an electric winch?

no..not allowed in NY finger lakes for whatever reason. If so I'd install as I have to let out all the strap and basically winch onto the boat...and thats with the fender buried in the water!
 

smokeonthewater

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Re: How to size a trailer for a boat??

If you decide that you want a bunk trailer, just find a good deal on one and sell this one... converting is less than ideal and not a cheap as you might think.
 

tractorboy

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Re: How to size a trailer for a boat??

If you decide that you want a bunk trailer, just find a good deal on one and sell this one... converting is less than ideal and not a cheap as you might think.

That's what I'm working through now. Your right may not cost effective for what I'm starting to see
 

JimS123

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Re: How to size a trailer for a boat??

From your pics it looks like you have an ideal setup, plus the size of the trailer looks real good! If I were looking for a used boat and saw your rig with that trailer under her, I'd jump at it in a minute.

I agree it rides high, but part of the reason is its not a low slung frame. Its not like you have a squatty cuddy, so what's the difference?

Don't take offense, but maybe you need some instructions on how to launch and load. The winch is there to load the boat, so the fact that you have to crank on 20' sounds proper to me. When I load mine I crank her up the full length of the trailer.

A couple of things to look at....
When the boat is off, make sure all the rollers are free. Lube them up just to be sure.
Next, be sure that you don't have any aft rollers that are higher than the keel. One time I inadvertently adjusted the last roller up too high and I could never get the boat to move. Once I moved the boat back a foot, it then came off like greased lightnin. I dropped the roller an inch and all was well after that.

"Bump and brake" isn't really a problem. I have one ramp I use that is nearly horizontal, plus shallow water besides. The only way I can launch there is a hard brake with the car. I'd hate to use that ramp with a bunk trailer. It would never come off, even if the front wheels of the car were under water!
 

JimS123

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Re: How to size a trailer for a boat??

no..not allowed in NY finger lakes for whatever reason. If so I'd install as I have to let out all the strap and basically winch onto the boat...and thats with the fender buried in the water!

I've been boating in the finger lakes for 43 years with an electric winch and haven't been stopped yet. Maybe they haven't caught me yet!

Even with my Powerwinch I let the cable out all the way. That's what the winch is for! Powerloading is frowned on in many places.
 

bonz_d

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Re: How to size a trailer for a boat??

That trailer does look a bit long but also looks like it fits very well. Looks like you could move the aft roller bunk all the way out to the frame rails to lower it though I don't think that's what I'd do.

Long isn't always a bad thing. The trailer I'm using was designed for a boat 14-16' long and the tongue does look long on it. But it is set up properly. The balance and tongue weight are good so the axle is also positioned correctly. The advantage with this comes as I launch at many very shallow ramps and the added length allows me to no have to back the truck into the water.

I was once at a ramp that was so shallow that I had to step out of the truck into the water and the transom of the boat still was not touching the water. Thank God for tiltbed roller trailers!
 
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