Most designers of trailerable boats do consider how to manage the stresses that their boats undergo when loaded onto a trailer and driven at speed down a bumpy road. The article is correct in saying that its much worse than the loadings that the boat endures when in the water, and if anyone has concerns about how to set their trailers up to suit, most of us designers will be happy to advise.
Not mentioned in the article is the importance of getting the tongue weight right. I will admit to not getting it right on my boat/trailer combination until this year. In my defense the boat comes out of the water once a year for bottom paint and then goes right back in again, roughly 10 miles round-trip with a maximum speed limit of 35 mph. I knew darn well it was tongue heavy which caused the back end of my tow vehicle to sag an awful lot and the trailer to exhibit way more flex than I would have been comfortable with over any greater distance and the stem was really taking a pounding from all that commotion. Taking advantage of having the trailer empty and blocked up while getting new tires (also very important) installed I shifted the axle forward enough to get the tongue weight where it should have been. The stanchion holding the winch was moved as well. All that effort paid off when I had a very smooth tow to the launch ramp. Don't be afraid to modify your trailer to fit your boat, most of the bits bolt onto the main frame making it easy to move stuff around. I have seen some axles welded to the frame, worth noting that when buying a trailer you think might need some adjustment.
Another "extreme" loading scenario can be seen at the end of the day while folks are loading their boats onto the trailers - please don't park the trailer so the tires remain dry, and then winch the boat over the fulcrum of the rear of the trailer. This puts your hull thru a terrible stress it was never intended to manage, and it's completely unnecessary. Boat trailer wheels & bearings are designed to go into the water. Do your bearing maintenance as required, and put your wheels far enough into the water so you can float your boat onto the first roller/bunk.
This article focusses on much heavier boats (he mentions 4,000 and 9,000 capacities!) than any trailer sailer I can think of. Good trailer with well ajusted rollers or bunks are quite ok with our lightweight boats.
Along the lines with what Mr. Welsford wrote, I worked out my hard riding trailer (boat and trailer bouncing off the road with pot holes). I had a trailer for a Force5 with it's dolly. Eight inch wheels. It was a small trailer... but with the recommended tire pressure, it bounced, high. As I tell you my resolution please note that this trailer spent aprox 150 (9000miles) hours rolling down the highways of eastern US to regattas. I remembered the Ford / Firestone lawsuit where tire pressure and side wall blowouts were the issue. So I lowered the tire pressure until side walls heated up, then I raised the pressure to where it didn't. 20 to 22 lbs of air pressure worked for those 8" four ply tires. I never had a problem and it rode wonderfully at an average of 65 to 70mph on the highways. Also, in the beginning with 55lbs of pressure, the strangest vibration (at over 55mph), would run right into the car from the trailer - I had to find a solution!
Speaking of the trailer doing more damage than anything, when I moved from Tennessee to Florida I towed The Lusty Slogger on the trailer that came with the boat 30 years before. I got to the lake, put the boat in the water, pulled the trailer out of the water and was driving off to park it when I noticed The Lustry Slogger was sinking. I quickly ran the trailer back into the lake but by now I had to start bailing the boat. I finally got the boat out of the water and saw where a bolt holding the bunk to the trailer was sticking up above the bunk and had punched a hole in the bottom of the boat. I found a shop that would repair the hole but made the mistake of telling them I was going back to Tennessee and would be in no rush to get it fixed! That turned into 4 trips back and forth and 6 weeks before he finally got around to fixing it. He did do an excellent job because for the next six years I owned the boat it didn't leak a drop through the hull (it did fill up with rainwater once and sank at the dock with only the dock lines keeping it from ending up at the bottom of the lake!
Most designers of trailerable boats do consider how to manage the stresses that their boats undergo when loaded onto a trailer and driven at speed down a bumpy road. The article is correct in saying that its much worse than the loadings that the boat endures when in the water, and if anyone has concerns about how to set their trailers up to suit, most of us designers will be happy to advise.
Not mentioned in the article is the importance of getting the tongue weight right. I will admit to not getting it right on my boat/trailer combination until this year. In my defense the boat comes out of the water once a year for bottom paint and then goes right back in again, roughly 10 miles round-trip with a maximum speed limit of 35 mph. I knew darn well it was tongue heavy which caused the back end of my tow vehicle to sag an awful lot and the trailer to exhibit way more flex than I would have been comfortable with over any greater distance and the stem was really taking a pounding from all that commotion. Taking advantage of having the trailer empty and blocked up while getting new tires (also very important) installed I shifted the axle forward enough to get the tongue weight where it should have been. The stanchion holding the winch was moved as well. All that effort paid off when I had a very smooth tow to the launch ramp. Don't be afraid to modify your trailer to fit your boat, most of the bits bolt onto the main frame making it easy to move stuff around. I have seen some axles welded to the frame, worth noting that when buying a trailer you think might need some adjustment.
Another "extreme" loading scenario can be seen at the end of the day while folks are loading their boats onto the trailers - please don't park the trailer so the tires remain dry, and then winch the boat over the fulcrum of the rear of the trailer. This puts your hull thru a terrible stress it was never intended to manage, and it's completely unnecessary. Boat trailer wheels & bearings are designed to go into the water. Do your bearing maintenance as required, and put your wheels far enough into the water so you can float your boat onto the first roller/bunk.
This article focusses on much heavier boats (he mentions 4,000 and 9,000 capacities!) than any trailer sailer I can think of. Good trailer with well ajusted rollers or bunks are quite ok with our lightweight boats.
Along the lines with what Mr. Welsford wrote, I worked out my hard riding trailer (boat and trailer bouncing off the road with pot holes). I had a trailer for a Force5 with it's dolly. Eight inch wheels. It was a small trailer... but with the recommended tire pressure, it bounced, high. As I tell you my resolution please note that this trailer spent aprox 150 (9000miles) hours rolling down the highways of eastern US to regattas. I remembered the Ford / Firestone lawsuit where tire pressure and side wall blowouts were the issue. So I lowered the tire pressure until side walls heated up, then I raised the pressure to where it didn't. 20 to 22 lbs of air pressure worked for those 8" four ply tires. I never had a problem and it rode wonderfully at an average of 65 to 70mph on the highways. Also, in the beginning with 55lbs of pressure, the strangest vibration (at over 55mph), would run right into the car from the trailer - I had to find a solution!
I've been on the look out for a used trailer for my new build, and appreciate the many good points! BestRoy
Speaking of the trailer doing more damage than anything, when I moved from Tennessee to Florida I towed The Lusty Slogger on the trailer that came with the boat 30 years before. I got to the lake, put the boat in the water, pulled the trailer out of the water and was driving off to park it when I noticed The Lustry Slogger was sinking. I quickly ran the trailer back into the lake but by now I had to start bailing the boat. I finally got the boat out of the water and saw where a bolt holding the bunk to the trailer was sticking up above the bunk and had punched a hole in the bottom of the boat. I found a shop that would repair the hole but made the mistake of telling them I was going back to Tennessee and would be in no rush to get it fixed! That turned into 4 trips back and forth and 6 weeks before he finally got around to fixing it. He did do an excellent job because for the next six years I owned the boat it didn't leak a drop through the hull (it did fill up with rainwater once and sank at the dock with only the dock lines keeping it from ending up at the bottom of the lake!