Trimaran - Especially Searunner - Owners

[bwickins]

Many thanks for such a quick and complete response . . . I´ll keep you up to date on my plans too . . .

[aquavitae]

Hello All,

Slowly rehabbing a 1982 - 37 ft Searunner here on St THomas. Two questions for the Searunner fraternity:

1.Decks are purported to be painted with Awlgrip but very slippery as old non-skid was painted over. Can I paint over the Awlgrip with Interlux Single part Brightside and embed nonskid in the new paint? Or do I have to sand the Awlgrip, apply primer coat and then use the Brightside with non-skid?

2. The 27 hp Yanmar spins a 13-inch, 3 blade fixed prop on a 1-inch shaft and boat will not do over 5 knots under power. Anyone have experience with the CDI perfect pitch props and especially the "extendo prop" ? This option looks like I could put a bigger prop on the boat (16 inch-2 blade) with out extending the prop shaft.

Input and advice gratefully welcomed.
Bob Petersen

[sassarassa]

Hi,

I don't know much about these things but I can share what my boat has.

My 37 has an 18hp Yanmar with a variable pitch auto stream prop - see seahawk dot com dot au (which I am not sure is the best option). It pushes the boat at 5.8 knots (gps) in flat water with no wind at 2900 RPM which is max revs. Any wind and I'm stuffed tho ... 15-20 knots and a bit of a sea on the nose and 3 knots is average

If you have a 27hp in a 37' searunner it should rocket along I would have thought?

It'd be interesting to hear what speed other 37 owners are getting? With the perfect prop could us 18hp owners get more than 6 knots? How much should the 27hp owners get? What size and pitch is recommended?

Sorry if I'm hijacking this question a little

cheers

Jon J


2. The 27 hp Yanmar spins a 13-inch, 3 blade fixed prop on a 1-inch shaft and boat will not do over 5 knots under power. Anyone have experience with the CDI perfect pitch props and especially the "extendo prop" ? This option looks like I could put a bigger prop on the boat (16 inch-2 blade) with out extending the prop shaft.

[PatnKarl]

Bob:
Q1. You can always put one-part (Brightsides) over two-Part (Awlgrip). The other way round, you need a primer because of the strong solvents in two-part, which can lift the one part. We had great success with Interlux 2 part Perfection. In the tropics, two part will give you longer life. We only got a couple years out of brightsides that we resorted to in our previous refit and have just finished our latest refit (our 4th! in 24 years) with 2 part.
For anti-skid we struggled to get a good texture for ourselves and the dog. We ended up putting down a coat of paint and, while wet, sprinkled anti-skid into it using a large spice bottle with shaker top. Then we overcoated to lock the anti-skid in. Worked well. We recommend anti-skid compound that absorbs paint so that it doesn't look dirty as the overcoat wears down. We'll see how long it lasts starting next year... we can't make it to the Caribbean this year. Hopefully we can meet someday and compare finishes!
Karl

[farotherside]

I went with Interlux Brightside over top of what was purportedly an International two-part epoxy paint last summer during my Searunner 37 refit, and IMHO it was a mistake.

The first coat of Brightside was too thick, and didn't dry. We had to take it all off! Add another loooooong week of work to the already-brutal summer. Stripped it all off and tried again - this time it dried, but it didn't stick to the epoxy paint. Maybe I didn't use enough solvent in the between coats? No idea, but after spending a thousand bucks on paint and a few hundred man-hours, my paintjob chips off with the slightest provocation.

If you have Awlgrip on there and it's sticking, STICK WITH IT. The extra cost involved in using a paint that you know is quality and you know works on your boat is money saved.

I went with the Interlux Brightside "Deckote" or whatever they call their antiskid product, which is just Brightside with grit and a flattening agent mixed in; you can buy the grit and flattening agent separately and mix it yourself if you prefer. I went with the 'fine' grit but after living with it for a year I now consider it far too fine for rough weather - it grips ok and doesn't ruin swimsuits, but wet bare feet don't find enough purchase for my liking. I should have gone with the 'coarse' version at the very least, and longer term I will very likely add another coat with extra grit.

If I had to do it again I would absolutely go with a two-part paint; nothing feels worse than standing around idle in a boatyard for a week, paying by the day, not knowing when or if your paint will ever actually dry. At least you *know* a two-part paint will harden up!

As for antiskid, the tip I got in the boatyard was to use fine bead-blasting beads, ie clear glass 'sand'. Apparently as the paint scuffs off the top of the beads, the fact that they are clear glass just shows the color of the paint underneath (ie white), and imparts a subtle 'reflective' look to the surface.

WHATEVER YOU DO, FOLLOW THE INSTRUCTIONS ON THE PAINT TO THE LETTER! I assumed that the more expensive the paint was, the easier it would be to use - not the case. I'm sure Brightside works well if you follow *every* step to the letter; strip the boat to the fiberglass, wash with Interlux solvents, prime one coat with Interlux primer, wash with solvent, wet sand, wash with solvent, prime a second coat with Interlux primer, wash with solvent, wet sand, wash with solvent, apply the first coat of Brightside...

Expect the paint job to take at least twice as long as your estimates, probably 3x to 4x as long! Every step on a deck the size of a Searunner takes hours and hours, and if you skip a step here and there you can easily wreck the whole paintjob. My Brightside comes off down to the primer with every accidental drop of a tool or impact of a block or shackle, and as best as I can tell it's that I forgot to do one of the washdowns with solvent between the primer coat and the Brightsides.

[Roy M]

Every ten years or so, I replace my deck nonskid. It's coming on to that time now, but I'm holding off to before I take off on cruise. Because I try to keep the weight down, it's easiest to simply strip off everything with a quality paint stripper. I do it one section at a time, stripping off the LPU, sand, etc., all the way to the base coat epoxy. If there are any cracks or other damage, I repair at this time. Then I give that section a coat of epoxy primer, consistent with my LP paint (Sterling, in my case). When everything is stripped and primed, I roll on my hull and cabinside color coat (Cloud White), then recoat as needed. Next I layout my nonskid pattern and tape it out with blue 3M tape,rounding the inside radius with a razor blade. Then I roll a layer of LP in the color I choose for my deck (Moon Dust), and immediately cast 30 grit sand to completely cover the wet surface. I paint only the alternating nonskidded areas so I am not disturbing the finish until it's complete. The next morning I vacuum the excess sand off, which leaves a perfect one-grain thick nonskid. I then apply a couple more coats of LPU to provide a totally opaque finish to the nonskid. Then I do the same to the remaining, unpainted sections of nonskid. Last, I pull the tape. Voila!

[blewett_john]

I can't find the photos. Could you please post a link.

Thanks,
John B.

[Jmolan]

John, not sure what photos you are asking about. There is a lot here.

Cruisers & Sailing Forums - Searunner Trimarans

Cruisers & Sailing Forums - Jmolan's Album: 34' Searunner San Carlos Mexico

I am currently 30 degrees (temp) 30 kts. of wind, hiding behind a tiny sand spit at 70 degrees north. But I got internet, amazing!

[Mark Johnson]

Originally Posted by aquavitae

Hello All,

Slowly rehabbing a 1982 - 37 ft Searunner here on St THomas. Two questions for the Searunner fraternity:

1.Decks are purported to be painted with Awlgrip but very slippery as old non-skid was painted over. Can I paint over the Awlgrip with Interlux Single part Brightside and embed nonskid in the new paint? Or do I have to sand the Awlgrip, apply primer coat and then use the Brightside with non-skid?

2. The 27 hp Yanmar spins a 13-inch, 3 blade fixed prop on a 1-inch shaft and boat will not do over 5 knots under power. Anyone have experience with the CDI perfect pitch props and especially the "extendo prop" ? This option looks like I could put a bigger prop on the boat (16 inch-2 blade) with out extending the prop shaft.

Input and advice gratefully welcomed.
Bob Petersen

PAINT: I would not consider painting over a two part paint with a one part paint. It would have about 1/5th the life span, and half the market value if you sell later...

PROPS: Your boat is WAY too slow, for having a 27 HP... We have an 18 hp Yanmar on out 34'er, and with a 15" Flex O Fold prop, and a clean hull, we can reach the low to mid 7s at full RPM. At our cruising RPM of 2,900, we go low to mid 6s. (In flat water with little headwind) In ocean waves and 20 knots on the nose... more like 5+.

Flex O Fold has the best thrust in fwd. of them ALL! A larger two blade is better than a smaller three blade, IF there is a minimum of 2" of blade tip clearance to the hull. (In thrust comparison... Prop size = total sq inches of blade surface, NOT OA dia.)

Prop selection is very specific stuff. The Mfgr. can help you get started. The goal is to have large enough blades & pitch, that you "just can" reach the engines "short term MAX RPM". (Ours = 3,600 RPM) You need to be able to reach this to ensure long engine life at a normal cruising RPM.

Many folding prop manufacturers will allow you to take your boat out for a short trial, and swap for more or less pitched blades. If anything... being slightly UNDER propped is better than over propped... At least as far as engine health.

NON SKID: Roy's technique is fine... tried and true. You get very consistent results... Some folks, as an alternative, use a base coat of wet Awl Grip high build primer, sprinkle the sand, let dry, vacuum, and apply several topcoats within the one day chemical bond "window"..

Personally, I have been leery of doing such large areas this way, and roll on the top coats with a large amount of Awl Grip's coarse "Griptex" IN the paint. I start on a warm day, early, and using spray catylist & fast solvents, I have rolled on 5 quite thin, but quite "grit filled" coats in a day, and gotten complete coverage. You must not work the roller a lot, to cover thin spots, or you lift the previous coat. You just let the next coat take care of it.

It will be time for us to repaint in a couple of years, and we have lost no grit. It is in fact plenty non skid... so I may just apply a couple of thin top coats, (After a good scotch brite & Ajax scrub). It may loose 10% of it's non skid properties, but it will be easier to clean, and still be non skid enough.

Good luck, M.

[Roy M]

I have a Yanmar 27 HP (3GM30) with an 18" Martec Mark III elliptical folding prop. I think the issue here is that someone may be expecting the impossible out of prop/engine HP combinations. We have planing hulls, so when the wind and sails cooperate, we fly like a cloud across the sea. The rest of the time we are prisoners of physics, meaning that we are constrained by hull speed determined by our waterline length, UNTIL the magic moment when we break free into the planing mode. It takes a big burst of available energy to achieve this state, one not available from a small engine. Think of it as a RIB dinghy with a 15 horse motor. Up to the point where the bow stops rising, we are pushing a wall of water with the engine. Goose the throttle and the bow breaks free and levels out, and the boat shoots over the surface. My boat maxes out under engine power at about 8 knots. The formula for hull speed in the displacement mode is about 1.4 times the square root of the waterline length. Coincidentally, in my case, about 8 knots. I would have to have a very powerful engine, spinning a very fast prop, to get me on a plane under pure engine power. That's what the sails are for.

[Boatguy30]

Can anyone tell me the size ply used in the Searunner 31 decks and cabin tops. I assume it is 3/8" but I know the hull sides are 1/4" Does anyone happen to know the camber in the topsides. I seem to recall my SR 34 plans showed 1" in 48", but wonder if it isn't more? Looking to apply general SR 31 scantlings to a similar technology 30' cat of around same displacement, but designer specs larger stringers, 3/8" ply and no camber. With a bit of camber in the topsides I should be able to reduce the ply thickness as well as increase the bunk with a bit.

Cheers,
Jeff

[Roy M]

A friend of mine, an industrial designer, is assisting me in creating my new hard dodger. As a prelim to the main event, he has transferred my lines drawing for the 40 into digital format, which I'm attaching. The next step is changing the lines to reflect the changes I made to the cockpit and sterncastle when I built it. Then we'll generate the design for the dodger. This is so cool.

[Mark Johnson]

Originally Posted by Roy M

A friend of mine, an industrial designer, is assisting me in creating my new hard dodger. As a prelim to the main event, he has transferred my lines drawing for the 40 into digital format, which I'm attaching. The next step is changing the lines to reflect the changes I made to the cockpit and sterncastle when I built it. Then we'll generate the design for the dodger. This is so cool.

Hi Roy,
Very cool indeed!

Great that you are finally getting into that dodger project. Ours was bar none the best mod to our Searunner, and made it where the enclosure worked so well, even at sea!

I don't remember if I told you when I sent pics years ago, but... First I made a full sized mock up out of 1/8" door skins & duct tape. This helped me get it just tall enough to sit under, but short enough to see over.

Then I copied the curvature of the cabin front, (A french curve BTW, more flat in the front 1/3rd). I then built a mold for vacuum bagging the layered ply front to this curve. It would later be tilted at a similar angle to the cabin front, but just a bit more.

The dodger top was a copy of the boat's cabin top curve, but scaled down. Then I built a mold to vacuum down the top piece, out of thin wood veneered skins over a Kledgacell core.

The sides I drew over and over, trying to mimic the lines of the day. (More of a Ford Mustang, than a Chevy Camaro...) They were tilted in at a similar angle to the cabin sides, but once again, just a bit more.

Next I copied the window "port" corner radiuses, still trying to match the boat. The idea is to NOT ugly up the lines of the boat with something that looks like it doesn't belong...

Finally, a cut out for the mast, sistered up a doubler (out of cored composites) here, to replace the strength lost from the cut out, and added a double curved stringer (down & back), on top, for attachment of the curtains.
Then an aft top edge "upper lip" as well as lower "drip lip".

Two small opening hatches were cut in the top for ventilation too... This is a must!

Since it has to be removable to move the mast fwd and service the CB, I made a flange all around the base (out of 1/4" ply), that matched perfectly the shapes of the mating cabin top. This facilitated a water tight, gasketed, bolt down attachment.

Two large people can stand on it, and until I added the 1/4" Lexan, It weighed in @ only 35#! The Lexan almost doubled that, and when I re-glaze it, I may downsize to 3/16" thick Lexan...

The large plastic front can expand & contract about 1/4", from "0" F. to "105" F!!! Be sure to take that into account in your attachment method. I used the good ol "nuts n bolts" method that has worked so well for us, and used barrel nuts in the dodger frame. The machine screw holes in the plastic need to be twice the size as the #10 screw, and full of GE SilPruf caulk. You can not screw down a piece of plastic this large, with this many screws, within the working time of any other caulk. (You need 45 minutes!)

We later learned the hard way... It not only needs Sunbrella covers for the 99% of the time NOT under way, but it needs to be 100% opaque. White definitely is not! The damage is done now, but we have hybrid covers that are a layer of white outside, and a layer of Forrest Green inside. This is reflective outside, but 100% opaque.

With enough 2000 grit sanding, then polishing, even badly damaged Lexan can be brought back to about 90%. I polish ours each season.

It was the best 1,200 + hours I ever spent! Best of luck with it,

Mark

[Roy M]

Mark, Thanks for the details and all of the great photos you have submitted over the last couple years. Mine is going to be quite similar. Good design is classic. Because I have a little more available space on the 40, we will probably make it a little "wilder". I'm thinking a nacelle over the companionway and a related boom arch over the aft cabin to hold some enclosure panels (and maybe photovoltaics), all supporting the overall lines of the original design. Trying to keep this project from ruining Jim's clean concepts is a critical requirement. But, as you have demonstrated, being warm and protected in nasty conditions is a necessity, as well as keeping the cockpit cool in the hot spells. This stuff isn't easy, that's why these solutions are so fraught with complexities that can spell disaster to the completed project. Hopefully, this will be a productive synthesis of design, engineering and fabrication, as yours is.

At any rate, I'll be submitting the designs to the forum as they emerge. Lonnie Pogue is a brilliant designer and local marine artist, and he got pretty excited by the idea of the dodger and offered to help. I'm trading him some boat work for his prodigious efforts. He's going to Photoshop some pics and superimpose the drawings so we can more easily visualize the possibilities. Then, it's time to start building the form, along the lines you have so clearly described. Thanks again for your inspiration and fine craftsmanship.

[HapaPops]

For non-skid. Kiwi grip.

Google it and thank me later.