Commander #155 'Mephisto Cat'

[Rico]

I had a trailer built when I found out I would have to move out of the country and had to store the Mephisto Cat out of the water for a while...

It is interesting that the best source for trailers of this sort is nowhere near the west coast...

The trailer is all steel galvanized with sealed wiring, and flush-equipped brakes for safe dipping in salt water. It is also equipped with an extra axle at the front end. The intent of this additional axle is to be able to launch the boat from the beach... Hopefully somewhere in the gulf of California (Sea of Cortez) someday (sailing down in Baja!) where there might not be a lift or an appropriate ramp available.

I would probably do the recovery at a location where a lift, or crane is available.

I have not used it in this manner yet...

Hull Profile / Dimensions for trailer or cradle.

The sketches/dimensions on the attached .Pdf will be helpful to anyone wanting to build a trailer or a cradle specifically for their Pearson Commander/Ariel.

(NOTE that the Ariel and Commander SHARE the very same hull design.)

This same measurement method is good for any other boat... provided you take these actual measurements for the intended hull!).

I had my trailer built with bunks for more gentle support while towing, but this information will also apply if you wish to use pads.

Credit for the ability to take these measurements should go to 'LITTLE GULL' which was on the hard, fairly level, and not too far from me in San Rafael. (And to her owner Ebb, who quickly made her available when I was in a bind to provide these measurements to build my trailer in a rush...)

Ebb, you may have noticed a few nail holes and pencil markings on the asphalt in August 2006... I used these to lay a grid on the ground below 'Little Gull' in order to take my measurements.

PICTURE: Sample from document below (attached as PDF)
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These are some notes on the dimensions and drawings in the PDF:

Drawings #1 and A1 (1-of-3 and 2-of-3)
Note the marked dimensions related to the descriptions below:

(A) Width (Thickness of the Keel)
The shape of the keel (in horizontal section) is similar to that of a wing. It has a bulbous leading edge measuring about
9" at its widest (Location 'a2' in Drawing A1). This tapers back to a mere 2-1/2" at its thinnest (Location 'a1' in Drawing A1). This is at the trailing edge as the keel ends to allow for the rudder. This dimensions occurr at a section close to the lowest point of the keel. If your trailer will have 'guides' to float the boat onto the trailer, you will need to allow for this width.

(B) Transom To back of Keel
Pretty Self-Explanatory; This Dimension is 82.5"

(C) Tansom to Center of Keel
Translation: Location of Center of Gravity (CG) This is a critical dimension for trailers as this will dictate where the trailer's axels are to be located. This will be an important one for your trailer buider. Easier to 'eyeball' on a fin keel; harder with a full keel as the ballast location is not so obvious. I calculated this approximately with a bit of math, but find that it must be fairly accurate as I am able to end up with a tongue weight of about 700-800lbs with the boat nicely centered on the axels.

This may seem like a big load on the tongue (it is!) but these boats are not light loads! Less tongue weight will leave you with potential uplift to the rear of your tow vehicle in uneven pavement, and this is not good as you might end-up FOLLOWING your boat down the freeway.

The Land Cruiser's max tongue weight is 900Lbs with a Load leveling device (Highly recommended! As it nicely transfers the load to the front of the tow vehicle and makes for a wonderful tow!)

Brakes on the trailer are also essential!! The boat and trailer will likely weigh WELL in excess of you & your tow vehicle!

(D) Bottom of Keel to Hull height
Not so critical for a full keel boat... Dimension D2 on Drawing A1 may be useful to someone...

(E) Transom To Bow length
LOA (Length overall) Dimension: 25'-7" (it really is this; just like the book says!)

(F) Length of Keel.
Translation: Bearing surface length of the Keel. I did not want to have the rudder shoe bearing any load as the boat sat on the trailer, so I deducted dimension 'H' from this measurement as noted in Drawing A1. The trailer's steel structural member goes the full length, but the treated 2x6 that actually bears the keel load is shorter, leaving the rudder shoe nicely up in the air.

(G) Bottom of Keel to Deck
This should be the dimension from the bottom of the keel to the bow eye. - I decided against installing a bow eye. My trailer has bunks, which in their cradling shape provide quite a bit of resistance to back/forth displacement on the trailer.
If I ended up relying on a bow eye to hold the boat, I'd have quite a few BIGGER issues to worry about...

The dimension I used is good for the Bow stop element incorporated into the trailer which you can see in the pictures above. I might have to slam on the brakes -but I do not think that I run the risk of accelerating out from underneath the boat...



Keel bunk measuring Guide (Page 3-of-3)

The dimensions listed are pretty accurate, but since Trailers/cradles have adjustable bunks or pads this accuracy is not that critical... although you do not want to be too high...

If the drawing might not be obvious or easily read; so here: the measurements are the dimensions of vertical lines starting from a horizontal plane at the bottom of the keel to the point where they intersect with the curvature of the hull.

One set of dimensions is taken from a line offset 20" from the centerline of the hull (inner set of bunks), while the other is at 30" from the centerline (outer set of bunks).

All measurements (towards the bow) marked 'Side' and those appearing to be missing are points that intersect with the hull plane above the waterline (where the nice paint is), or do not touch the Hull at all. (- For example; at 27' and 30' from the Commander's transom there is no longer any boat for pads/bunks to reach!)


Other Dimensions (Page 4 in the .Pdf)

This page adds a few additional dimensions not listed in the previous drawings that may be useful to both Ariel and Commander owners.

Please let me know if you are using this as reference - Just so I know if it is useful - AND especially if you have any different findings from the dimensions / data that I need to update.