CONTINUOUSWAVE

Hi. I've been looking at the 190 and 210 Montauk as my first boat. Everything looks good on paper. One question still on my mind though: how do I estimate the true towing weight?

On the Boston Whaler website, the 210 Montauk is said to weigh 3,464-lbs with "engine, fuel, and water if applicable". Add about 700-lbs for a trailer, it's 4,400-lbs. One of my tow vehicles has a towing capacity of only 5,000-lbs, so I'd like to stay under that for maximal flexibility.

Is that a safe estimate? Or do I need to worry about other necessary things that can push it over 5,000-lbs?

Thanks a lot.

Typically a vehicle (in the USA) has a specified towing capacity, but that figure assumes that there is absolutely no added weight in the vehicle itself; if there are passengers or luggage or anything else in the vehicle, you must subtract that added weight from the rated towing capacity. The only exception is the driver. On that basis, you should not expect that a vehicle rated to tow 5,000-lbs will be able to actually tow something that weighs 5,000-lbs unless the vehicle is completely empty and has only a driver.

The total weight of a boat, engine, trailer, fuel, gear, and who knows what else will tend to be higher than any figure you add up. The best way to really know the total towed weight is to weigh the trailer on a certified scale. But expect it to weigh more than you estimated.

You should allow for the weight of fuel. You can figure that gasoline weighs about 6.25-lbs per gallon. The total weight of fuel in the vehicle and boat can add up fast. For example, my truck has a 42-gallon tank and the boat has a 77-gallon tank. If I were to tow with both tanks filled to capacity, I would have about 740-lbs of fuel that should be considered as part of the total load on the vehicle.

In the instance being discussed here, having a 5,000-lbs tow-rated vehicle and a 4,400-lbs trailer load sounds like you will probably be within specifications, assuming you don't plan to tow with four 200-lbs adult passengers in the vehicle and a 200-lbs cooler in the boat. That additional 1,000-lbs would have to be considered.

In addition to total towed weight, you should also consider the weights on the tow vehicle drive axle--I assume you have a rear-wheel drive vehicle. The tongue weight of the trailer can add considerable weight on the rear axle, which has a separate weight rating specified by the manufacturer. Also check the maximum tire loads on the rear axle tires; the tire ratings may not be as high as the axle rating.

There is an good archive in the archives about using a scale to find all sorts of weights involved in towing. I highly recommend reading that article. You can find it at

Boat Weight From Certified Scale
http://continuouswave.com/ubb/Forum1/HTML/016667.html

Thanks! I didn't know passengers and luggage in the vehicle also need to be counted. In that case things can quickly go above 5,000lbs, even with the smaller 190 Montauk. Guess I'll have to settle on the other tow vehicle, which is rated for 7,000lbs.

When contemplating tow ratings and actual weights, other considerations are distances, roads, speeds, and grades that will be traveled. If you are towing short distances, on paved roads, at moderate speeds, with very gentle grades, having a load near maximum rated tow-rating won't be a big concern. On the other hand, if you plan to tow long distances on interstate highways at speeds of 60-MPH or more and will have to climb and descend steep grades, having a vehicle with a tow capacity that very comfortably exceeds the actual towed weight will be much appreciated.

Re what counts against towed weight: get the manufacturer's official towing guide and read it carefully.

Here is an example, taken from the 2017 FORD Towing Guide.
http://www.fleet.ford.com/towing-guides/

For a FORD EXPEDITION with 3.5-liter V6, 3.15 rear axle, two-wheel drive, and optional CLASS IV Heavy-Duty Trailer Tow Package, the listings say "Maximum Loaded Trailer Weight" 9,200-lbs. However, in a footnote the listings also caution:

...Make sure vehicle payload (reduced by option weight) will accommodate trailer tongue load weight and weight of passengers and cargo added to towing vehicle. Addition of trailer tongue load weight and weight of passengers and cargo cannot cause vehicle weights to exceed rear GAWR or GVWR. These ratings can be found on the vehicle Safety Compliance Certification Label.

This can interpreted to mean that you can still tow the rated maximum loaded trailer weight, as long as there is not too much added weight in the form of vehicle options, passengers, or luggage that causes the gross axle weight rating (GAWR) (for either front or rear axle) or gross vehicle weight rating (GVWR) to be exceeded. GAWR is a maximum load on the axles, and typically the rear axle will be the limiting factor. GVWR is a rating that includes the ability of the vehicle to come to a stop with its brakes and for its suspension to work properly. The gross combined weight rating (GCWR), the total weight of the vehicle and trailer, is also given.

In the case of this FORD EXPEDITION, the GCWR is 14,900-lbs. If a trailer of maximum weight, 9,200-lbs, is attached, this leaves 5,700-lbs for the total weight of the vehicle, options, passengers, and gear in the vehicle. To find exactly how much a particular FORD EXPEDITION will weigh, you may have to resort to weighing it, unless the manufacturer happens to give you that figure. Usually data about an individual vehicle appears on a sticker, usually found on the door frame of the driver side door. The actual vehicle weight may be given there, or maybe not. I have an image of a load capacity sticker for a FORD EXPEDITION (that I was thinking about buying), but I don't see the actual weight given there, nor is it given on the OEM window sticker. Sometimes the state licensing agency knows the vehicle weight--I assume they get it from the VIN. In my state (Michigan) the registration just gives the weight as a category, not actual weight.

Let's suppose we have this EXPEDITION loaded to the max, that is, to a GVWR limit of 7,500-lbs. If GCWR is 14,900-lbs, then we get a maximum trailer weight of 14,900 - 7,500 = 7,400-lbs, which is quite a bit less than the rated maximum of 9,200-lbs. This is how you can figure out the maximum amount of added weight in the vehicle.

Looking at it another way, take the GCWR (14,900) and subtract the maximum towed weight (9,200) to find the maximum vehicle weight (in this case it would be 5,700-lbs). Then go weigh the vehicle with all your gear and passengers to see if it exceeds the maximum weight permitted for GCWR (which in this case was 5,700-lbs). For every pound the vehicle is over, you have to reduce the towed trailer weight so that you stay under the GCWR limit.

The rear axle gear ratio is another influence on tow ratings. These days any larger vehicle--your typical full-size SUV or truck--is getting below-fleet-average fuel economy. The manufacturers must meet a federal regulation for fleet average fuel economy. This means they want to make every vehicle get the best fuel economy it can. As a result, they don't build SUV or truck vehicles with the best gear ratio for towing; they build them for the best gear ratio for fuel economy--and that is the worst gear ratio for towing. Usually to get the best towing capacity you have to special order the vehicle or find the one or two per hundred that were built with the best towing capacity. Lots of big SUVs are built to get better gas mileage and won't ever tow anything.

When you go shopping for a tow vehicle, pay attention to the gear ratio, as it often determines the towing capacity.